This document provides an overview of thermometric titration. Some key points:
- Thermometric titration measures temperature changes that occur during chemical reactions to locate endpoints precisely. It has advantages over subjective visual methods.
- The temperature change observed is directly proportional to the heat of reaction and moles of analyte. Second derivatives of temperature curves can precisely locate inflection points.
- Parameters like mixing, probe placement, data density, and software filtering must be optimized for accurate results.
- Applications include acid-base, redox, precipitation, and complexometric titrations. Common determinations include acids, bases, and metal ions.
This document discusses thermometric titration, where the endpoint of a titration reaction is determined by measuring the temperature change. Key points:
- Titrant is added continuously and the temperature change is measured, with the endpoint identified by an inflection point on the temperature curve.
- The temperature change observed is directly related to the enthalpy change of the reaction.
- Factors like heat losses, temperature differences between titrant and analyte, and stirring must be controlled for accurate results.
- Automated systems use burets for precise titrant addition, a thermistor probe for temperature measurement, and software for data collection and endpoint determination.
- Parameters like mixing, probe placement,
Electron spin resonance (ESR) spectroscopy is a technique used to study compounds with unpaired electrons. In ESR, a sample is placed in a static magnetic field and irradiated with microwaves. This causes transitions between the electron spin energy levels. The absorption of microwave energy is detected to obtain an ESR spectrum. ESR spectra provide information about electron environments through parameters like g-values and hyperfine splitting patterns. ESR finds applications in studying transition metal complexes and unstable free radicals.
The document provides information about electroanalytical methods of analysis. It defines electroanalytical methods as techniques that study analytes by measuring potentials or currents in an electrochemical cell containing the analyte. It discusses various types of electroanalytical techniques including potentiometry, voltammetry, and Karl Fischer titration. It provides details on the principles, instrumentation, applications, and advantages of these analytical methods.
It contains what are the shift reagents, and how they will use in NMR spectroscopy. It includes lanthanide shift reagents and their effect using NMR spectroscopy. It has mostly used shift reagents like Europium and their importance. paramagnetic species that affect the NMR spectra are also explained in detail. What are contact shift and pseudo-contact shift also explained. It contains what are the chiral shift reagent, and the advantages, and disadvantages of lanthanide shift reagents. Reference books are also included.
Electrogravimetry is a method used to separate and quantify ions of a substance, usually a metal, through electrolysis. The analyte solution is electrolyzed, causing the analyte to deposit on the cathode. The cathode is weighed before and after the experiment, and the mass difference is used to calculate the amount of analyte originally present. There are two types of electrogravimetry - constant current electrolysis, where the current is kept constant, and constant potential electrolysis, where the potential is kept constant. In both cases, the deposited analyte on the cathode is measured through changes in mass to determine the concentration in the original solution.
Coulometry is an electroanalytical technique where the amount of electricity (in coulombs) required to complete an electrochemical reaction is measured. There are two main types - potentiostatic coulometry, where the potential is held constant, and coulometric titration with a constant current. The quantity of electricity is directly proportional to the amount of analyte and can be used to determine concentrations. Coulometry has applications in inorganic analysis, analysis of radioactive materials, microanalysis, and determination of organic compounds.
It include all the thermal methods widely used in large and small scale industries with detailed applications and examples for explanations.
Medha Thakur (M.Sc Chemistry)
This document provides an overview of coulometry, which is an electroanalytical technique used for quantitative analysis. There are two forms of coulometry: controlled-potential coulometry and controlled-current coulometry. Both techniques involve completely oxidizing or reducing an analyte and measuring the total charge passed to determine the amount of analyte. Controlled-potential coulometry applies a constant potential while controlled-current coulometry applies a constant current. Factors like electrolysis time, electrode area, and stirring rate affect the analysis. Coulometry is used to quantify both inorganic and organic analytes.
This document discusses thermometric titration, where the endpoint of a titration reaction is determined by measuring the temperature change. Key points:
- Titrant is added continuously and the temperature change is measured, with the endpoint identified by an inflection point on the temperature curve.
- The temperature change observed is directly related to the enthalpy change of the reaction.
- Factors like heat losses, temperature differences between titrant and analyte, and stirring must be controlled for accurate results.
- Automated systems use burets for precise titrant addition, a thermistor probe for temperature measurement, and software for data collection and endpoint determination.
- Parameters like mixing, probe placement,
Electron spin resonance (ESR) spectroscopy is a technique used to study compounds with unpaired electrons. In ESR, a sample is placed in a static magnetic field and irradiated with microwaves. This causes transitions between the electron spin energy levels. The absorption of microwave energy is detected to obtain an ESR spectrum. ESR spectra provide information about electron environments through parameters like g-values and hyperfine splitting patterns. ESR finds applications in studying transition metal complexes and unstable free radicals.
The document provides information about electroanalytical methods of analysis. It defines electroanalytical methods as techniques that study analytes by measuring potentials or currents in an electrochemical cell containing the analyte. It discusses various types of electroanalytical techniques including potentiometry, voltammetry, and Karl Fischer titration. It provides details on the principles, instrumentation, applications, and advantages of these analytical methods.
It contains what are the shift reagents, and how they will use in NMR spectroscopy. It includes lanthanide shift reagents and their effect using NMR spectroscopy. It has mostly used shift reagents like Europium and their importance. paramagnetic species that affect the NMR spectra are also explained in detail. What are contact shift and pseudo-contact shift also explained. It contains what are the chiral shift reagent, and the advantages, and disadvantages of lanthanide shift reagents. Reference books are also included.
Electrogravimetry is a method used to separate and quantify ions of a substance, usually a metal, through electrolysis. The analyte solution is electrolyzed, causing the analyte to deposit on the cathode. The cathode is weighed before and after the experiment, and the mass difference is used to calculate the amount of analyte originally present. There are two types of electrogravimetry - constant current electrolysis, where the current is kept constant, and constant potential electrolysis, where the potential is kept constant. In both cases, the deposited analyte on the cathode is measured through changes in mass to determine the concentration in the original solution.
Coulometry is an electroanalytical technique where the amount of electricity (in coulombs) required to complete an electrochemical reaction is measured. There are two main types - potentiostatic coulometry, where the potential is held constant, and coulometric titration with a constant current. The quantity of electricity is directly proportional to the amount of analyte and can be used to determine concentrations. Coulometry has applications in inorganic analysis, analysis of radioactive materials, microanalysis, and determination of organic compounds.
It include all the thermal methods widely used in large and small scale industries with detailed applications and examples for explanations.
Medha Thakur (M.Sc Chemistry)
This document provides an overview of coulometry, which is an electroanalytical technique used for quantitative analysis. There are two forms of coulometry: controlled-potential coulometry and controlled-current coulometry. Both techniques involve completely oxidizing or reducing an analyte and measuring the total charge passed to determine the amount of analyte. Controlled-potential coulometry applies a constant potential while controlled-current coulometry applies a constant current. Factors like electrolysis time, electrode area, and stirring rate affect the analysis. Coulometry is used to quantify both inorganic and organic analytes.
Electrogravimetric analysis involves the quantitative deposition of an analyte onto an electrode through electrolysis. There are two main types: constant current electrolysis, where the current is kept constant and the potential varies, and controlled potential electrolysis, where the potential is kept constant to selectively deposit analytes. Electrogravimetric analysis can be used for quantitative analysis, separation, preconcentration of analytes, and electrosynthesis.
In DSC the heat flow is measured and plotted against temperature of furnace or time to get a thermo gram. This is the basis of Differential Scanning Calorimetry (DSC).
The deviation observed above the base (zero) line is called exothermic transition and below is called endothermic transition.
The document provides information on rotational spectroscopy and the rotational spectra of molecules. It discusses key topics like:
1) Classification of molecules as linear, symmetric top, spherical top, and asymmetric top based on their moments of inertia.
2) The rigid rotor model and how it leads to quantized rotational energy levels expressed by the rotational constant B.
3) The selection rule for rotational transitions of ΔJ = ±1, which results in a series of equally spaced spectral lines.
4) Factors that determine the intensity of rotational lines, including Boltzmann distribution of molecular populations and degeneracy of energy levels.
These are chemical shift reagents and solvent induced shifts have their application in resolving the NMR Spectra of complex structures by inducing shift with respect to reference compound. Thus useful in interpretation of structures of complex organic compounds.
Electron Spin Resonance (ESR) SpectroscopyHaris Saleem
Electron Spin Resonance Spectroscopy
Also called EPR Spectroscopy
Electron Paramagnetic Resonance Spectroscopy
Non-destructive technique
Applications
Extensively used in transition metal complexes
Deviated geometries in crystals
This document summarizes voltammetry, an electrochemical method that uses a three-electrode system to obtain information about analytes. A voltage ramp is applied to the working electrode to reduce ions, while current is measured. Common types of voltammetry include cyclic, square wave, differential pulse, and stripping voltammetry. The working electrode potential is varied over time, while the reference electrode potential remains constant. Voltammetry can be used to determine metal ion concentrations, for wastewater analysis, and in various other applications due to its low detection limits and ability to handle high salt concentrations.
Coulometry is an electroanalytical technique that measures the quantity of electricity required for a chemical reaction. There are two main types - controlled potential coulometry (potentiostatic coulometry) and controlled current coulometry (galvanostatic coulometry). Controlled potential coulometry involves holding the working electrode at a constant potential to allow exhaustive electrolysis of the analyte without interfering reactions. The quantity of electricity passed is proportional to the analyte concentration and is measured with an electronic integrator. Applications include determination of metal ions, microanalysis, and analysis of radioactive materials like uranium.
Partition function indicates the mode of distribution of particles in various energy states. It plays a role similar to the wave function of the quantum mechanics,which contains all the dynamical information about the system.
This document discusses evidence for covalent bonding in metal complexes. It explains that electron-electron repulsion is less in complexes than free metal ions due to delocalization of electrons over ligand orbitals. This is known as the nephelauxetic effect. The nephelauxetic parameter (β) quantifies this effect, with softer ligands having a smaller β value. Electron paramagnetic resonance (EPR) spectroscopy provides further evidence, as the spectra of complexes show interaction between the ligand nuclear spin and electrons of the metal ion.
The document discusses the lability and inertness of coordination complexes. It defines labile complexes as those where ligand exchange occurs rapidly, while inert complexes have slow ligand exchange. Lability is determined by factors like the metal ion size, charge, and d-electron configuration, not thermodynamic stability. Smaller or higher charged metal ions and complexes with less than 3 d-electrons tend to be more labile. The rate of ligand substitution depends on both the leaving and entering ligands. Steric effects and solvent also influence the rate. Complexes may undergo dissociative or associative substitution based on their structure.
This document provides an overview of interfacial electrochemistry. It discusses how interfaces form boundaries between different phases of matter and influence interactions with the environment due to changed atomic structures. Most electrochemical events occur at interfaces, making interfacial electrochemistry important. When two dissimilar materials contact, charge separation occurs across the interface, creating an interfacial potential difference. The document also describes models of the electrical double layer that forms at electrode-electrolyte interfaces, such as the Helmholtz-Perrin and Gouy-Chapman models.
Mass spectroscopy for M Sc I Chemistry SPPUsiraj174
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of ions. It involves converting the sample into gaseous ions, separating the ions based on their mass-to-charge ratio, and detecting the relative abundance of each ion. There are four key stages: ionization, acceleration, deflection according to mass-to-charge ratio, and detection. Different types of peaks in a mass spectrum provide information about the molecule, including the molecular ion peak, which indicates the molecular mass, and fragment ion peaks, which result from fragmentation of the molecular ion. Rules like the nitrogen rule and rule of 13 can help determine molecular formulas from mass spectrometry data.
Chronopotentiometry is an electrochemical technique that applies a constant current between electrodes and measures the potential over time. It can be used to investigate electroporation of bilayer lipid membranes. When a constant current is applied, the potential gradually changes as oxidation and reduction reactions occur at the electrodes. Ultimately, the concentration of one species is depleted at the electrode surface, causing a rapid change in potential. Chronopotentiometry provides simple information about membrane pores but is not well-suited for studying capacitive currents.
High frequency Titrations is an analytical technique in which a radio frequency electric field is applied for which electric conductance of analytical substance governs the response of detector.
This document discusses electrogravimetry, which is the quantitative analysis of substances by electrolysis. It defines key terms used in electrogravimetry like cathode, anode, current density, and overpotential. It explains Faraday's laws of electrolysis and how they relate to the amount of material deposited. It also describes how controlling variables like cathode potential can be used to selectively deposit metals and separate them from each other.
This document discusses phosphorescence spectroscopy and provides information about molecular luminescence, including fluorescence and phosphorescence. It describes the basic principles, including how molecules are excited to higher energy states and then emit light as they relax to lower energy states. Singlet and triplet states are defined, along with electronic and vibrational energy levels. Electron transitions like internal conversion, intersystem crossing, and vibrational relaxation are explained. Instrumentation for measuring phosphorescence is also summarized, including components like light sources, monochromators, sample cells, and detectors. Some applications of phosphorescence are mentioned, such as in television screens, pigments, and glow-in-the-dark toys.
This document discusses applications of cyclic voltammetry (CV). CV is an electrochemical technique useful for studying electrode reactions. It involves applying a continuous, cyclic potential to a working electrode in a cell containing three electrodes. The document outlines the principle, working, and applications of CV, including quantitative analysis, studying chemical reactivity and redox processes, determining thermodynamic properties, kinetics, and more. Examples are given of using CV to characterize modified electrodes and study interactions like of anticancer drugs with DNA.
This document discusses several thermal analysis techniques including differential thermal analysis (DTA). It explains that DTA involves heating a sample and inert reference material simultaneously and measuring any temperature difference, which can indicate physical or chemical changes in the sample. The document provides details on DTA instrumentation, the factors that can affect DTA results, and applications such as material identification and purity assessment by comparing DTA curves.
The document discusses the manufacturing process of parenteral preparations. It describes parenterals as sterile liquids or solids for injection or implantation. The manufacturing process involves planning, material management, production, quality control testing, filling, and packaging. Production areas are divided into strict zones based on cleanliness. Environmental controls and facility design aim to prevent contamination, with areas for filling, weighing, storage, and administration. Personnel flow and utility locations are also considered for efficiency.
Electrogravimetric analysis involves the quantitative deposition of an analyte onto an electrode through electrolysis. There are two main types: constant current electrolysis, where the current is kept constant and the potential varies, and controlled potential electrolysis, where the potential is kept constant to selectively deposit analytes. Electrogravimetric analysis can be used for quantitative analysis, separation, preconcentration of analytes, and electrosynthesis.
In DSC the heat flow is measured and plotted against temperature of furnace or time to get a thermo gram. This is the basis of Differential Scanning Calorimetry (DSC).
The deviation observed above the base (zero) line is called exothermic transition and below is called endothermic transition.
The document provides information on rotational spectroscopy and the rotational spectra of molecules. It discusses key topics like:
1) Classification of molecules as linear, symmetric top, spherical top, and asymmetric top based on their moments of inertia.
2) The rigid rotor model and how it leads to quantized rotational energy levels expressed by the rotational constant B.
3) The selection rule for rotational transitions of ΔJ = ±1, which results in a series of equally spaced spectral lines.
4) Factors that determine the intensity of rotational lines, including Boltzmann distribution of molecular populations and degeneracy of energy levels.
These are chemical shift reagents and solvent induced shifts have their application in resolving the NMR Spectra of complex structures by inducing shift with respect to reference compound. Thus useful in interpretation of structures of complex organic compounds.
Electron Spin Resonance (ESR) SpectroscopyHaris Saleem
Electron Spin Resonance Spectroscopy
Also called EPR Spectroscopy
Electron Paramagnetic Resonance Spectroscopy
Non-destructive technique
Applications
Extensively used in transition metal complexes
Deviated geometries in crystals
This document summarizes voltammetry, an electrochemical method that uses a three-electrode system to obtain information about analytes. A voltage ramp is applied to the working electrode to reduce ions, while current is measured. Common types of voltammetry include cyclic, square wave, differential pulse, and stripping voltammetry. The working electrode potential is varied over time, while the reference electrode potential remains constant. Voltammetry can be used to determine metal ion concentrations, for wastewater analysis, and in various other applications due to its low detection limits and ability to handle high salt concentrations.
Coulometry is an electroanalytical technique that measures the quantity of electricity required for a chemical reaction. There are two main types - controlled potential coulometry (potentiostatic coulometry) and controlled current coulometry (galvanostatic coulometry). Controlled potential coulometry involves holding the working electrode at a constant potential to allow exhaustive electrolysis of the analyte without interfering reactions. The quantity of electricity passed is proportional to the analyte concentration and is measured with an electronic integrator. Applications include determination of metal ions, microanalysis, and analysis of radioactive materials like uranium.
Partition function indicates the mode of distribution of particles in various energy states. It plays a role similar to the wave function of the quantum mechanics,which contains all the dynamical information about the system.
This document discusses evidence for covalent bonding in metal complexes. It explains that electron-electron repulsion is less in complexes than free metal ions due to delocalization of electrons over ligand orbitals. This is known as the nephelauxetic effect. The nephelauxetic parameter (β) quantifies this effect, with softer ligands having a smaller β value. Electron paramagnetic resonance (EPR) spectroscopy provides further evidence, as the spectra of complexes show interaction between the ligand nuclear spin and electrons of the metal ion.
The document discusses the lability and inertness of coordination complexes. It defines labile complexes as those where ligand exchange occurs rapidly, while inert complexes have slow ligand exchange. Lability is determined by factors like the metal ion size, charge, and d-electron configuration, not thermodynamic stability. Smaller or higher charged metal ions and complexes with less than 3 d-electrons tend to be more labile. The rate of ligand substitution depends on both the leaving and entering ligands. Steric effects and solvent also influence the rate. Complexes may undergo dissociative or associative substitution based on their structure.
This document provides an overview of interfacial electrochemistry. It discusses how interfaces form boundaries between different phases of matter and influence interactions with the environment due to changed atomic structures. Most electrochemical events occur at interfaces, making interfacial electrochemistry important. When two dissimilar materials contact, charge separation occurs across the interface, creating an interfacial potential difference. The document also describes models of the electrical double layer that forms at electrode-electrolyte interfaces, such as the Helmholtz-Perrin and Gouy-Chapman models.
Mass spectroscopy for M Sc I Chemistry SPPUsiraj174
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of ions. It involves converting the sample into gaseous ions, separating the ions based on their mass-to-charge ratio, and detecting the relative abundance of each ion. There are four key stages: ionization, acceleration, deflection according to mass-to-charge ratio, and detection. Different types of peaks in a mass spectrum provide information about the molecule, including the molecular ion peak, which indicates the molecular mass, and fragment ion peaks, which result from fragmentation of the molecular ion. Rules like the nitrogen rule and rule of 13 can help determine molecular formulas from mass spectrometry data.
Chronopotentiometry is an electrochemical technique that applies a constant current between electrodes and measures the potential over time. It can be used to investigate electroporation of bilayer lipid membranes. When a constant current is applied, the potential gradually changes as oxidation and reduction reactions occur at the electrodes. Ultimately, the concentration of one species is depleted at the electrode surface, causing a rapid change in potential. Chronopotentiometry provides simple information about membrane pores but is not well-suited for studying capacitive currents.
High frequency Titrations is an analytical technique in which a radio frequency electric field is applied for which electric conductance of analytical substance governs the response of detector.
This document discusses electrogravimetry, which is the quantitative analysis of substances by electrolysis. It defines key terms used in electrogravimetry like cathode, anode, current density, and overpotential. It explains Faraday's laws of electrolysis and how they relate to the amount of material deposited. It also describes how controlling variables like cathode potential can be used to selectively deposit metals and separate them from each other.
This document discusses phosphorescence spectroscopy and provides information about molecular luminescence, including fluorescence and phosphorescence. It describes the basic principles, including how molecules are excited to higher energy states and then emit light as they relax to lower energy states. Singlet and triplet states are defined, along with electronic and vibrational energy levels. Electron transitions like internal conversion, intersystem crossing, and vibrational relaxation are explained. Instrumentation for measuring phosphorescence is also summarized, including components like light sources, monochromators, sample cells, and detectors. Some applications of phosphorescence are mentioned, such as in television screens, pigments, and glow-in-the-dark toys.
This document discusses applications of cyclic voltammetry (CV). CV is an electrochemical technique useful for studying electrode reactions. It involves applying a continuous, cyclic potential to a working electrode in a cell containing three electrodes. The document outlines the principle, working, and applications of CV, including quantitative analysis, studying chemical reactivity and redox processes, determining thermodynamic properties, kinetics, and more. Examples are given of using CV to characterize modified electrodes and study interactions like of anticancer drugs with DNA.
This document discusses several thermal analysis techniques including differential thermal analysis (DTA). It explains that DTA involves heating a sample and inert reference material simultaneously and measuring any temperature difference, which can indicate physical or chemical changes in the sample. The document provides details on DTA instrumentation, the factors that can affect DTA results, and applications such as material identification and purity assessment by comparing DTA curves.
The document discusses the manufacturing process of parenteral preparations. It describes parenterals as sterile liquids or solids for injection or implantation. The manufacturing process involves planning, material management, production, quality control testing, filling, and packaging. Production areas are divided into strict zones based on cleanliness. Environmental controls and facility design aim to prevent contamination, with areas for filling, weighing, storage, and administration. Personnel flow and utility locations are also considered for efficiency.
This document discusses differential scanning calorimetry (DSC), providing an overview of the technique in 3 paragraphs or less. It describes DSC as a technique that measures the difference in heat flow between a sample and reference material as they are heated. The document outlines some of the main components of a DSC including sample pans, purge gas, and cooling systems. It also briefly discusses sample preparation, the working principle of DSC, interpreting DSC curves, and some common applications and types of DSC instruments.
This document provides an overview of differential scanning calorimetry (DSC). DSC is a thermal analysis technique that measures the heat absorbed or released by a sample as it is heated, cooled, or held at constant temperature. It can be used to analyze properties such as glass transition temperatures, melting points, heat capacity, and more. The summary discusses:
1) DSC works by heating a sample and reference simultaneously while measuring the heat differential between the two. This allows it to detect endothermic and exothermic reactions in the sample.
2) Key measurements include glass transition temperatures, crystallization/melting points, and heats of reaction.
3) A typical DSC curve will
Thermal analysis techniques measure properties of a sample as a function of temperature. Differential scanning calorimetry (DSC) measures the heat flow into or out of a sample relative to a reference as both are heated. DSC can identify phase transitions like melting or glass transitions through endothermic or exothermic events. Common applications include determining melting points, characterizing materials, and analyzing polymer mixtures. DSC provides both quantitative and qualitative information about physical and chemical changes.
Differential scanning calorimetry (DSC) is a thermal analysis technique that measures the heat flow into or out of a sample as it is heated, cooled, or held at constant temperature. DSC directly measures the energy required to establish a zero temperature difference between a sample and an inert reference material as both are subjected to an identical temperature program. This allows the determination of transition temperatures such as melting points and glass transition temperatures. DSC is commonly used in pharmaceutical analysis to characterize materials such as purity determination, polymorphism detection, and stability studies. The basic components of a DSC instrument include sample and reference pans, a furnace to heat the pans at a controlled rate, and sensors to measure the heat flow difference between
3rd Year Undergraduate Cyclic Voltammetry PracticalJames McAssey
1. This document describes using cyclic voltammetry to study the ferrocyanide/ferricyanide redox couple. Key parameters such as peak potentials, currents, and diffusion coefficients are obtained from cyclic voltammograms.
2. Experiments are conducted using a glassy carbon working electrode in solutions of known ferrocyanide concentration. Multiple scans are run at varying scan rates to determine diffusion coefficients from the peak currents.
3. Analysis of peak potentials and currents allows determining the redox potential, verifying the number of electrons transferred, and quantifying the diffusion coefficients of both redox forms. Diffusion coefficients provide insight into the redox process and can be used to determine unknown concentrations.
The investigation of thermodynamic properties and reactivity yields interesting insights into the chemistry of newly synthesized substances. With thermal analysis extensive information can be gained from small samples (often only a few milligrams). In addition, the data obtained by thermal analysis can be used to plan and optimize a synthesis. Among the most important applications are identification and purity analysis, and the determination of characteristic temperatures and enthalpies of phase transitions (melting, vaporization), phase transformations, and reactions. Investigations into the kinetics of consecutive reactions and decomposition reactions are also possible. With the instruments available today such analyses can usually be performed quickly and easily. In this review the fundamentals of thermoanalytical methods are described and illustrated with selected examples of applications to low and high molecular weight compounds.
Ppp Dsc 1 Thermal Analysis Fundamentals Of Analysisguest824336
Thermal analysis techniques such as differential scanning calorimetry (DSC) are used to investigate polymer properties as a function of temperature. DSC provides information on glass transition temperatures, crystallization temperatures, melting points, and heat capacity by measuring the heat flow into or out of a small polymer sample as it is heated or cooled. Proper sample preparation and experimental parameters are important to obtain accurate and reproducible DSC results.
This document provides an introduction to cyclic voltammetry for non-electrochemists. Cyclic voltammetry uses an electric charge as an input to study redox reactions at an electrode surface. It can provide information about surface area, morphology, reaction sites, impurities, adsorption properties, and more. The document outlines the theory behind cyclic voltammetry, including factors that affect output current like double layer charging, charge transfer, mass transport, and scan rate. It also discusses applications like determining redox potentials and diffusion coefficients.
This document provides an overview of differential thermal analysis (DTA) and differential scanning calorimetry (DSC). It discusses the principles, instrumentation, applications, and advancements of both techniques. DTA involves measuring the temperature difference between a sample and reference material as they are heated. DSC measures the heat flow into or out of a sample during phase transitions. The document outlines the components of DTA and DSC instruments and provides examples of how they are used to characterize materials and identify physical and chemical changes.
This document provides an overview of electrochemistry techniques used in clinical chemistry, including potentiometry, voltammetry, coulometry, and conductometry. It describes the basic concepts such as electrochemical cells and electrodes. Potentiometry techniques like ion-selective electrodes and their applications in measuring electrolytes are discussed in detail. Other techniques like amperometry and different types of voltammetry and coulometry are also summarized along with their uses and advantages.
The document discusses differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). DSC measures heat flow during phase transitions and can identify glass transitions, crystallization, and melting. TGA measures weight loss from decomposition as temperature increases. Both techniques provide information on thermal properties like heat capacity, transition temperatures, and decomposition temperatures. Samples are heated at a constant rate while measuring properties like heat flow, weight, or gas evolution to characterize materials.
Thermal analytical methods such as differential scanning calorimetry (DSC) are important tools used in drug development to provide quantitative information about physical and chemical changes in materials as a function of temperature. DSC can be used to determine properties like melting points, glass transition temperatures, crystallization behavior, purity, and reaction kinetics. Samples are prepared in small pans and calibrated using standard reference materials before interpretation of transitions identified on DSC thermograms, which can indicate properties like polymorphism, purity according to established equations, or whether a compound is crystalline or amorphous. DSC finds regulatory use for characterization and is described in pharmacopeias with requirements for experimental documentation.
Thermal analysis techniques such as differential thermal analysis (DTA) and differential scanning calorimetry (DSC) measure the difference in temperature or heat flow between a sample and a reference material as they undergo a controlled temperature program. These techniques can be used to characterize materials through measurements of phase transitions, glass transitions, melting points, crystallization, and chemical reactions. DTA and DSC provide both qualitative and quantitative information about physical and chemical changes in materials.
Voltammetry involves applying a potential to a working electrode and measuring the resulting current. It can characterize redox reactions through parameters like peak potentials and currents in cyclic voltammetry. Cyclic voltammetry cycles the potential of a working electrode versus a reference electrode and measures the current. It is used to study redox processes and obtain information about reaction kinetics and mechanisms. The peak separation and shapes of cyclic voltammograms provide information about whether redox processes are reversible or irreversible.
This document discusses Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). TGA measures the change in weight of a sample during heating or cooling, while DSC measures the heat absorbed or released by a sample during phase transitions or chemical reactions. Both techniques provide information about physical and chemical changes in materials as functions of temperature. The document describes the principles, instrumentation, experimental procedures, sources of error, and applications of TGA and DSC for characterizing materials.
Differential thermal analysis and differential scanning calorimetry are thermal analysis techniques that involve measuring physical properties of a sample as it is heated or cooled. In differential thermal analysis, the temperature difference between a sample and inert reference is measured as the sample undergoes physical or chemical changes. Differential scanning calorimetry directly measures the heat flow into or out of a sample as it is heated or cooled. Both techniques provide information about phase transitions, purity, crystallinity, and reactions in polymers, pharmaceuticals, minerals, and other materials.
This document discusses differential thermal analysis (DTA), which measures the difference in temperature between a sample and a reference material as both are heated. It describes phenomena like physical changes (melting, vaporization) and chemical reactions that cause temperature changes detectable by DTA. Instrumentation for DTA is also outlined, including furnaces, temperature programmers, and amplifiers. Factors that can affect DTA curves like heating rate, atmosphere, sample mass, and particle size are examined. Differential scanning calorimetry (DSC) is also introduced as a related technique.
This document discusses polymorphism as part of a preformulation study seminar. It defines polymorphism as the ability of a substance to exist in two or more crystalline forms that have different molecular arrangements. The key points covered include:
- The need to study polymorphism to select the most stable and soluble form for formulations. Metastable forms often have better bioavailability.
- Various methods to identify and characterize polymorphs such as X-ray diffraction, thermal analysis techniques like DSC and TGA, and microscopy.
- Factors that can influence polymorphic transitions like temperature, humidity, solvents, grinding, and compression during tableting.
- The importance of understanding polymorphism for properties like
Thermal analysis refers to measuring a physical property of a sample as it is heated or cooled at a controlled rate. This document discusses several thermal analysis techniques including thermogravimetry (TG), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). TG measures weight changes as a function of temperature, DSC measures heat flows, and DTA measures temperature differences between a sample and reference. Thermal analysis is useful for determining phase transitions, thermal stability, and structural changes of materials like polymers. The instrumentation for TG typically includes a high precision balance, furnace, temperature controller, and data recorder. Interpretation of TG curves provides information about chemical reactions and decomposition processes occurring in a sample as it
This document discusses analyzing the error of thermocouples using a controlled temperature profile method. Thermocouples are placed inside a controlled heating profile and their readings are collected over time as the thermocouples degrade. The readings are analyzed using various signal processing techniques like smoothing, FFT filtering, and outlier detection to characterize thermocouple drift and error. Experimental results like temperature readings, outlier detection, and histograms are presented and compared to theoretical models of thermocouple error. The controlled temperature profile method allows more accurate analysis of thermocouple error compared to traditional calibration methods.
This document provides an overview of common thermal analytical techniques including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). DSC measures the heat flow into or out of a sample as it is heated or cooled. TGA measures the change in mass of a sample as it is heated. DTA measures the temperature difference between a sample and inert reference as both are heated. The document describes the basic principles, components, and applications of these thermal analysis techniques for characterizing materials.
This document discusses various thermal analysis techniques including thermogravimetric analysis (TGA), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). TGA measures the mass change of a sample as it is heated or cooled at a controlled rate. DTA detects physical or chemical changes in a sample by measuring the difference in temperature between the sample and an inert reference. DSC measures the heat absorbed or released by a sample during physical transitions or chemical reactions as it is heated or cooled. The document describes the basic principles, instrumentation, applications, and factors affecting the results of these thermal analysis methods.
This document provides information about differential scanning calorimetry (DSC), including its basic principles, instrumentation, sample preparation, and applications. DSC measures the difference in heat flow between a sample and reference material as they are subjected to controlled temperature changes. It can be used to determine properties like melting points, glass transitions, purity, and kinetics. The document discusses how DSC works, sample handling procedures, and the types of thermal events that can be observed in a DSC curve.
A MEMS thermal biosensor is described for metabolic monitoring applications. It consists of a thermal sensor chip integrated with a microfluidic system featuring two chambers - one for a sample solution and one for a reference buffer. Changes in temperature difference during biochemical reactions can be measured by the thermopile and indicate concentration changes. The device operates in either a flow-injection or flow-through mode. Fabrication involves depositing nickel and chromium layers for heaters and thermopiles, etching a backside cavity, and bonding a PDMS microfluidic chip. The sensor offers improved sensitivity for thermal monitoring of biochemical processes.
Thermogravimetric analysis (TGA) measures the change in mass of a sample as it is heated. In a TGA experiment, a sample is placed in a furnace that increases in temperature at a controlled rate while the sample mass is continuously monitored with a microbalance. A TGA curve plots the percentage mass change over time or temperature. TGA can be used to determine decomposition temperatures of materials, measure purity and stability, and study thermal decomposition mechanisms of organic, inorganic, and polymeric compounds.
This document provides an overview of thermogravimetric analysis (TGA). TGA involves measuring the mass of a substance as it is heated or cooled over time in a controlled temperature program. It summarizes the principle, instrumentation, example curve, applications, limitations, and factors affecting results of TGA. The instrumentation section describes the sample holder, microbalance, programmable furnace, temperature control/sensor, and data readout components of a TGA instrument. Common applications include determining thermal stability, material characterization, and compositional analysis.
Thermogravimetric analysis (TGA) involves measuring the weight of a substance as it is heated, and can be used to analyze mixtures, determine drying temperatures, and study reaction kinetics. TGA works by heating a sample in a furnace while precisely measuring its weight on a high-precision balance. Derivative thermogravimetric analysis (DTGA) measures the rate of weight change during heating. TGA can identify different components in a mixture based on their unique thermal decomposition profiles, and determine optimum drying ranges to isolate compounds like calcium oxalate. Kinetic parameters of reactions can also be extracted from TGA or DTGA curves using dynamic or isothermal methods.
Differential thermal analysis and it's pharmaceutical applicationJp Prakash
Differential thermal analysis (DTA) is a thermal analysis technique that measures the temperature difference between a sample and an inert reference material as both are subjected to a controlled temperature program. DTA can detect physical and chemical changes that involve endothermic or exothermic processes, such as melting, crystallization, oxidation, and decomposition. DTA is widely used in pharmaceutical applications to characterize materials and determine phase transitions, decomposition temperatures, and thermal stability. The document provides examples of DTA studies on sulfur, benzoic acid, and the antihypertensive drug telmisartan to illustrate how DTA can identify physical and chemical changes that occur as temperature is varied.
Thermal analysis techniques such as differential thermal analysis (DTA) measure the temperature difference between a sample and an inert reference material as they are heated or cooled. DTA can identify physical and chemical changes in materials through endothermic or exothermic peaks on a thermogram. The DTA instrument contains sample and reference holders connected to thermocouples which are heated in a furnace and temperature differences are amplified, detected and recorded. DTA has applications in determining melting points, phase changes, and reactions, as well as characterizing materials like polymers, pharmaceuticals, soils and catalysts. It can also provide information on purity, thermal stability and kinetic parameters of organic materials.
Application of microcalorimeter in stability studyPrashant Patel
Microcalorimetry is an advanced form of calorimetry that can measure very small quantities of heat involved in chemical and physical processes. It works by measuring the temperature changes that occur as a result of exothermic or endothermic reactions in the sample. There are various types of microcalorimeters classified based on their operating principles, including adiabatic, heat conduction, and power compensation calorimeters. Microcalorimetry has many applications in pharmaceutical stability studies, including drug-excipient compatibility testing and studying degradation kinetics of drugs. It provides advantages over conventional stability testing methods by being more sensitive and not requiring sample dissolution.
This document discusses Thermo gravimetric analysis (TGA), a technique where the weight of a substance is recorded as it is heated or cooled at a controlled rate. TGA is used to detect changes in mass that occur due to thermal events like desorption, absorption, and chemical reactions. Results are displayed as Thermo gravimetric (TG) curves that plot mass change versus temperature or time. The curves reveal temperatures where mass loss occurs due to decomposition or evaporation, as well as temperatures where the material is stable. TGA can be used to identify materials based on their characteristic temperature ranges of decomposition. Modern TGA instruments precisely measure weight changes, can rapidly heat and cool samples, and are often coupled to additional analytical techniques.
it is a method of miscellaneous instrumental analytical technique. it is one of the thermal analytical techniques used. it also has wide applications in the field of pharmacy.
The different type of thermal analysis: principle, instrumentation, advantages, disadvantages, applications, working data, Curve, topology, differences
This document provides instructions for an experiment to study and calibrate temperature sensors using a resistance temperature detector (RTD) and thermistor. The procedure involves measuring the resistance of the RTD and thermistor at various temperatures using a constant temperature bath. Curve fitting the resistance-temperature data allows determining the temperature coefficients (α for RTD, β for thermistor) that characterize each sensor's resistance change with temperature. The experiment aims to understand how RTDs and thermistors can be used for temperature measurement and their calibration.
Thermistors and resistance temperature detectors (RTDs) are common temperature sensors that function by changing electrical resistance with temperature. Thermistors have a high temperature coefficient, making them sensitive to small temperature changes, while RTDs use metals like platinum that change resistance linearly with temperature. Both sensor types require multi-wire connections to compensate for wire resistance and accurately measure the sensor's resistance change due only to temperature.
Thermal analysis methods such as differential scanning calorimetry (DSC) can provide both qualitative and quantitative information about physical and chemical changes in materials as a function of temperature. DSC instruments work by measuring the heat flow into a sample as it is heated, cooled, or held isothermally. This allows the instrument to detect transitions like glass transitions, melting points, crystallization events, and chemical reactions. Key components of DSC instruments include the sample holder, furnace, temperature programmer, recording device, and atmosphere control. DSC has many applications in fields like pharmaceutical analysis, materials characterization, and reaction kinetics studies.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
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ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
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Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
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Answers about how you can do more with Walmart!"
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
2. Contents
1. Introduction
2. Thermometric titration
3. Apparatus and setup of automated
thermometric titration
4. Optimization of thermometric titration
parameters
5. Application
6. Reference
3. Introduction
Thermometric titration is one of a number of instrumental titration
techniques where endpoints can be located accurately and precisely
without a subjective interpretation on the part of the analyst as to their
location. Enthalpy change is arguably the most fundamental and
universal property of chemical reactions, so the observation of
temperature change is a natural choice in monitoring their progress.
It is not a new technique, with possibly the first recognizable
thermometric titration method reported early in the 20th century (Bell
and Cowell, 1913).
In spite of its attractive features, and in spite of the considerable
research that has been conducted in the field and a large body of
applications that have been developed; it has been until now an under-
utilized technique in the critical area of industrial process and quality
control.
The temperature changes observed during a thermometric titration are
the consequence of the heat evolved or absorbed by the reaction
between the analyte & the reagent. The heat or enthalpy of a reaction
∆H is given by the familiar thermodynamic expression.
∆H=∆G + T∆S
Where T is the temperature. ∆G is the free energy change & ∆S is the
entropy change for the reaction. The change in the temperature ∆T
during thermometric titration is given by,
4. ∆T= -n∆H/K where n is the no. of moles of reactant and K is the heat
capacity of the system. Thus, the total change in temperature is directly
proportional to the no. of moles of analyte.
Thermometric titration
In the thermometric titration, titrant is added at a known constant rate
to a titrand until the completion of the reaction is indicated by a change
in temperature. The endpoint is determined by an inflection in the
curve generated by the output of a temperature measuring device.
Consider the titration reaction:
aA + bB = pP
Where:
A = the titrant, and a = the corresponding number of moles
reacting
B = the analyte, and b = the corresponding number of moles
reacting
P = the product, and p = the corresponding number of moles
produced
At completion, the reaction produces a molar heat of reaction ΔHr
which is shown as a measurable temperature change ΔT. In an ideal
system, where no losses or gains of heat due to environmental
influences are involved, the progress of the reaction is observed as a
constant increase or decrease of temperature depending respectively
on whether ΔHr is negative (indicating an exothermic reaction) or
positive (indicating an endothermic reaction). In this context,
environmental influences may include:
5. Heat losses or gains from outside the system via the vessel walls and cover;
Differences in the temperature between the titrant and the titrand;
Evaporative losses from the surface of the rapidly mixed fluid;
Heats of solution when the titrant solvent is mixed with the analyte solvent;
Heat introduced by the mechanical action of stirring(minor influence); and
Heat produced by the thermistor itself (very minor influence).
Figure1. Idealized thermometric titration plots of exothermic (left) and endothermic (right) reactions
The shape of experimentally obtained thermometric titration plots will
vary from such idealized examples, and some of the environmental
influences listed above may have impacts. Curvature at the endpoint
might be observed. This can be due to insensitivity of the sensor or
where thermal equilibrium at the endpoint is slow to occur. It can also
occur where the reaction between titrant and titrand does not proceed to
stoichiometric completion. The determinant of the degree to which a
reaction will proceed to completion is the free energy change. If this is
favourable, then the reaction will proceed to be completion and be
essentially stoichiometric. In this case, the sharpness of the endpoint is
dependent on the magnitude of the enthalpy change. If it is
unfavourable, the endpoint will be rounded regardless of the magnitude
6. of the enthalpy change. Reactions where non-stoichiometric equilibria
are evident can be used to obtain satisfactory results using a
thermometric titration approach. If the portions of the titration curve
both prior to and after the endpoint are reasonably linear, then the
intersection of tangents to these lines will accurately locate the endpoint.
This is illustrated in Figure 2.
Figure 2. Representation of a thermometric titration curve for a reaction with a non-
stoichiometric equilibrium
Consider the reaction for the equation aA + bB = pP which is non-
stoichiometric at equilibrium. Let A represent the titrant, and B the
titrand. At the beginning of the titration, the titrand B is strongly in
excess, and the reaction is pushed towards completion. Under these
conditions, for a constant rate of titrant addition the temperature increase
is constant and the curve is essentially linear until the endpoint is
approached. In a similar manner, when the titrant is in excess past the
endpoint, a linear temperature response can also be anticipated. Thus
intersection of tangents will reveal the true endpoint.
7. An actual thermometric titration plot for the determination of a strong
base with a strong acid is illustrated in Figure 3.
Typical thermometric titration plot of an exothermic reaction
The most practical sensor for measuring temperature change in
titrating solutions has been found to be the thermistor. Thermistors are
small solid state devices which exhibit relatively large changes in
electrical resistance for small changes in temperature. They are
manufactured from sintered mixed metal oxides, with lead wires
enabling connection to electrical circuitry. The thermistor is
encapsulated in a suitable electrically insulating medium with
satisfactory heat transfer characteristics and acceptable chemical
resistance. Typically for thermistors used for chemical analysis the
encapsulating medium is glass, although thermistors encapsulated in
epoxy resin may be used in circumstances where either chemical attack
(e.g., by acidic fluoride-containing solutions) or severe mechanical
stress is anticipated. The thermistor is supported by suitable electronic
circuitry to maximize sensitivity to minute changes in solution
temperature. It is capable of resolving temperature changes as low as
10–5 K.
8. Figure4. Thermometric probe for thermometric titration system
A critical element in modern automated thermometric titrimetry is the
ability to locate the endpoint with a high degree of reproducibility. It is
clearly impractical and insufficient for modern demands of accuracy and
precision to estimate the inflection by intersection of tangents. This is
done conveniently by derivatization of the temperature curve. The
second derivative essentially locates the intersection of tangents to the
temperature curve immediately pre- and post- the breakpoint.
Thermistors respond quickly to small changes in temperature such as
temperature gradients in the mixed titration solution, and thus the signal
can exhibit a small amount of noise. Prior to derivatization it is therefore
necessary to digitally smooth (or “filter”) the temperature curve in order
to obtain sharp, symmetrical second derivative “peaks” which will
accurately locate the correct inflection point. This is illustrated in Figure
5. The degree of digital smoothing is optimized for each determination,
and is stored as a method parameter for application every time a titration
for that particular analysis is run.
9. Fig. 5. Location of a thermometric titration endpoint using the second derivative of a digitally
smoothed temperature curve
Apparatus and setup for automated
thermometric titrimetry
A suitable setup for automated thermometric titrimetry comprises the
following:
• Precision fluid dispensing devices – burets – for adding titrants and
dosing of other reagents.
• Thermistor-based thermometric sensor.
• Titration vessel (100-250mL) in adiabatic condition.
• Stirring device, capable of highly efficient stirring of vessel contents
without splashing.
• Computer with thermometric titration operating system.
• Thermometric titration interface module – this regulates the data
flow (0.1-1.0 mL/min) between the burets, sensors and the computer.
To obviate volume corrections and to minimize temperature variations
between the titrant and sample, the titrant concentration is usually 100
10. times greater than that of the reactant. For thermistor that has a
resistance of 2kΩ and a sensitivity of -0.04 ohm ohm-1
deg-1
Celsius in
the 250
C temperature range, a change of 0.010
C corresponds to an
imbalance potential of 0.157mV. Temperature of the titrand and
sample should be within 0.20
C before a titration is begun. A small
heating element, located inside the titration vessel, can be used to
warm the sample to the temperature of the titrant.
Basic thermometric titration system featuring 859 Titrotherm interface module and 800 Dosino dispensing
devices.
A = dosing device
B = thermometric sensor
C = stirring device
D = thermometric titration interface module
E = computer
Schematic of the relationship between the components in an automated thermometric titration system.
11. Optimization of thermometric titration
Parameters
1. Mixing
The thermistors used in the Thermoprobe thermometric probes
employed with Titrotherm have a response time of approximately 0.3
seconds. Most of the instrumental noise evident in thermometric
titrations is thus due to the detection of temperature gradients in the
stirred titration solution. Minimization of instrumental noise can
therefore be obtained by using stirring speeds as high as possible
consistent with the avoidance of splashing. Some compromise to
stirring speed might be necessary when working with determinations
where very little heat is evolved or absorbed, and where environmental
influences such as solvent evaporation might have a deleterious impact.
2. Probe orientation
It has been observed by a number of workers in the field of
thermometric titration that there is an optimum placement of the
thermistor probe and the buret delivery tip in the titration vessel. This
is at the periphery of the titration vessel, with the thermistor upstream
of the delivery tip when referred to the direction of flow in the vessel.
This relative placement permits the thorough mixing and thus most
efficient reaction of titrant and analyte.
3. Data density
Richter and Tinner (2001) have emphasized the importance of data
density around titration breakpoints in order to define endpoints
precisely. It has been stated previously that thermometric titrations are
conducted at constant titrant addition rates, and so the practice of
slowing down the titrant addition rates in potentiometric «dynamic
titrations » to obtain higher data densities around breakpoints is not an
option. Instead, the Titrotherm thermometric titration software
12. permits data density to be preset before the start of the titration. The
data density stays constant over the entire titration. With Titrotherm
software, the analyst has the option of altering the sampling rate of the
output from the thermometric sensor in the range of 5 to 25 times per
second. The maximum permissible number of data points that can be
collected during the course of a titration is 32’000. The data sampling
rate is matched to the anticipated titrant consumption and to the
titrant addition rate of the determination. Table 1 indicates the
relationship between titrant consumption, data sampling rate and
titrant addition rate. Higher titrant addition rates demand
concomitantly higher data sampling rates with the converse applying
for lower titrant addition rates.
4. Optimizing titration results with software
The Titrotherm software employs a powerful data-smoothing algorithm
that exhibits a minimum endpoint shift as a function of the degree of
filtering applied. However, it is inevitable that some shift will occur. For
highest accuracy and precision this shift should be taken into
consideration. For thermometric titrations, endpoint shift appears to be
less pronounced in titration reactions involving large enthalpy changes
with fast reaction kinetics. For example, redox and strong acid/strong
base titrations usually exhibit a minimal endpoint shift. Apart from
these, some reactions may require more careful optimization. Figure 6
and Table 2 illustrate the effect of the filter factor on the endpoint peak
shape and the endpoint shift. The titration illustrated was the
determination of nickel using sodium dimethylglyoximate as titrant.
13. FIG 6 filter factor =20 Fig 6 filter factor=50
Fig 6 filter factor=80 Fig 6 filter factor=100
For a rigorous optimization, an examination of the effect of filter factor
on the titrant consumption of the determination should be undertaken.
Table 2 and Figure 7 illustrate this process.
By plotting the filter factor (x-axis) against the titrant consumption
determined (y-axis), it can be seen in the example illustrated in Figure 7
14. that stable endpoint values are obtained over a filter factor range of
30…60. An optimal filter factor could thus be found in the range 40…50.
Fig 7 Determination of optimal filter factor
Application of thermometric titration
Thermometric titrimetry can be used for the following reaction types:
• Acid-base (acidimetry and alkalimetry)
• Redox
• Precipitation
• Complexometric
Acid-base titrations
1 Determination of fully dissociated acids and bases
The heat of neutralization of a fully dissociated acid with a fully
dissociated base (see Figure 8) is approximately –56 kJ/mol and can be
15. calculated as a standard enthalpy of reaction using standard enthalpies
of formation.
The reaction is strongly exothermic and thus provides an excellent basis
for a wide range of analyses in industry. An advantage for the industrial
analyst is that the use of stronger titrants (1…2 mol/L) permits a
reduction of the sample preparation effort. Samples can often be
directly and accurately dispensed into the titration vessel prior to
titration.
FIG 8 -Titration of NaOH with 1 mol/L HCl.
Hydrogen carbonate can be unequivocally determined in the presence
of carbonate by titration with hydroxyl ions (see Figure 9). The standard
enthalpy of reaction is approximately –41 kJ/mol.
16. FIG9- Titration of HCO3 – in company with CO3
2
– by 1 mol/L NaOH.
2. Titration of weak acids
Weakly dissociated acids yield sharp endpoints when titrated with a
strong base (see Figure 10).
FIG10- Titration of weak acids with 1 mol/L NaOH.
3. Titration of acid mixtures
Mixtures of complex acids can be resolved by thermometric titration
with standard NaOH in aqueous solution (see Figure 11 and Table 3). In
a mixture of nitric, acetic and phosphoric acids used in the fabrication
of semiconductors, three endpoints could be predicted on the basis of
the dissociation constants of the acids:
17. ------
Table 3-Titration of a mixture of nitric, acetic and phosphoric acid with 2 mol/L NaOH.
The key to determine the amount of each acid present in the mixture is
the ability to obtain an accurate value for the amount of phosphoric
acid present, as revealed by titration of the third proton of H3PO4.
FIG11- Titration of a mixture of nitric, acetic and phosphoric acid with 2 mol/L NaOH.
4.Non-aqueous acid-base titrations
Non-aqueous acid-base titrations can be carried out advantageously by
thermometric means. Acid leach solutions from some copper mines can
contain large quantities of Fe(III) as well as Cu(II). The «free acid»
(sulfuric acid) content of these leach solutions is a critical process
parameter. While thermometric titrimetry can determine the free acid
content with modest amounts of Fe(III), in some solutions the Fe(III)
content is so high as to cause serious interference. Complexation with
18. necessarily large amounts of oxalate is undesirable due to the toxicity
of the reagent. A thermometric titration was devised by diluting the
aliquot with 2-propanol (isopropyl alcohol, propan-2-ol) followed by
titration with standard KOH in 2-propanol. As a result, most of the
metal content precipitated prior to the start of the titration, and a
clear, sharp endpoint indicating the sulfuric acid content was obtained
(see Figure 12).
FIG12 - Determination of free H2SO4 in copper leach solution by titration in 2-propanolwith 1 mol/L KOH
in 2-propanol.
Redox titrations
1. Titrations with permanganate and dichromate
Redox reactions are normally strongly exothermic and can make
excellent candidates for thermometric titrations. Consider the classical
determination of ferrous ions with permanganate.
19. The determination of hydrogen peroxide by permanganate titration is
even more strongly exothermic:
This reaction is catalyzed by the presence of Mn2+. To avoid a sudden
surge of temperature shortly after commencement of the titration, it is
necessary to add a minute amount of Mn2+ prior to the start.
Other common titrants used in redox titrimetry can be employed. Due
to its purity and stability, potassium dichromate has been used
successfully as a titrant in the determination of Fe(II) and ascorbic acid
(vitamin C).
Complexometric (EDTA) titrations
Thermometric titrations employing sodium salts of
ethylenediaminetetra-acetic acid (EDTA) have been demonstrated for
the determination of a range of metal ions. Reaction enthalpies are
modest, so titrations are normally carried out with titrant
concentrations of 1 mol/L. This necessitates the use of the tetrasodium
salt of EDTA rather than the more common disodium salt, which is
saturated at a concentration of only approximately 0.25 mol/L.
An excellent application is the sequential determination of calcium and
magnesium. Although calcium reacts exothermically with EDTA (heat of
chelation approximately –23.4 kJ/mol), magnesium reacts
endothermically with a heat of chelation of approximately +20.1
kJ/mol. This is illustrated in the titration plot of EDTA with calcium and
magnesium in sea water (Figure 13). Following the solution
temperature curve, the breakpoint for the calcium content (endpoint
on the left in Figure 13) is followed by a region of modest temperature
rise due to competition between the heats of dilution of the titrant
with the solution, and the endothermic reaction of Mg2+ and EDTA.
20. The breakpoint for the consumption of Mg2+ (endpoint on the right in
Figure 13) by EDTA is revealed by an upswing in temperature purely
caused by heat of dilution.
FIG13 EDTA titration of calcium and magnesium in sea water.
Direct EDTA titrations with metal ions are possible when reaction
kinetics is fast as is the case with zinc, copper, calcium and magnesium.
However, with slower reaction kinetics such as those exhibited by
cobalt and nickel, back-titrations are used. Titrations for cobalt and
nickel are carried out in an ammoniacal environment; buffered with
ammonia/ ammonium chloride solution. An excess of EDTA is added
and back-titrated with Cu(II) solution (see Figure 14). It is postulated
that the breakpoint is revealed by the difference in reaction enthalpies
between the formation of the Cu-EDTA complex, and that for the
formation of the Cu-ammine complex.
21. FIG14 Titration plot of back-titration of excess EDTA with Cu(II) in NH3 /NH4Cl-buffered solution.
A catalyzed endpoint procedure to determine trace amounts of metal
ions in solution (down to approximately 10 mg/L) employs 0.01 mol/L
EDTA. This has been applied to the determination of low level Cu(II) in
specialized plating baths and to the determination of total hardness in
water. The reaction enthalpies of EDTA with most metal ions are often
quite low. Therefore titrant concentrations typically around 1 mol/L are
employed with correspondingly high amounts of analyte in order to
obtain sharp, reproducible endpoints. Using a catalytically indicated
endpoint in combination with a back-titration, very low EDTA titrant
concentrations can be used. An excess of EDTA solution is added.
The excess of EDTA is back-titrated with a suitable metal ion such as
Mn2+ or Cu2+. At the endpoint, the first excess of metal ion catalyzes a
strongly exothermic reaction between a polyhydric phenol (such as
resorcinol) and hydrogen peroxide (see Figure 15).
22. FIG 15 Thermometric EDTA titration of trace Cu(II) by back-titration with Mn(II), in combination with
catalytically enhanced endpointdetection using theexothermicreaction between hydrogen peroxideand
a polyhydric phenol.
Precipitation titrations
Thermometric titrimetry is particularly suited to the determination of a
range of analytes where a precipitate is formed by reaction with the
titrant. It may be employed for applications that cannot be satisfactorily
analyzed by potentiometric titrimetry.
1. Titration of sulfate
Sulfate may be rapidly and easily titrated thermo metrically using
standard solutions of Ba2+ as titrant. Industrially, the procedure has
been applied to the determination of sulfate in brine (including
electrolysis brines), in nickel refining solutions and particularly
for sulfate in wet process phosphoric acid, where it has proven to be
quite popular. The procedure can also be used to assist in the analysis
23. of complex acid mixtures containing sulfuric acid where resorting to
titration in non-aqueous media is not feasible.
The reaction enthalpy for the formation of barium sulfate is a modest –
18.8 kJ/mol. This can place a restriction on the lower limit of sulfate in a
sample that can be analyzed.
2.Titration of anionic and cationic surfactants
Anionic and cationic surfactants can be determined thermometrically
by titrating one type against the other. For instance, benzalkonium
chloride (a quaternary type cationic surfactant) may be determined in
cleaners and algaecides for swimming pools and spas by titrating with a
standard solution of sodium dodecyl sulfate (see Figure 16a).
Alternatively, anionic surfactants such as sodium lauryl sulfate can be
titrated with cetyl pyridinium chloride (see Figure 16b).
24. FIG 16A-Titration of benzalkonium chloride with sodium dodecyl sulfate. FIG 16B-Titration of sodium
lauryl sulfate in shampoo by titration with cetyl pyridinium chloride. Acetonitrile added to repress
micellerelated phenomena. Note sudden rise in temperature immediately prior to the endpoint.
Thermometric titrimetry offers an opportunity to observe the influence
of micelles on the conduct of the determination. To avoid the influence
of micelle-related phenomena on the outcome of the titration, it is
sometimes necessary to add a suitable solvent such as acetonitrile.
Reference
www.metrohm.com/com/.../Titration/BasicsThermometricTitration.html
www.creative-chemistry.org.uk/alevel/module2/.../N-ch2-08.pdf
Instrumental methods for chemical analysis by H. willard