Gravimetric analysis determines the amount of analyte by measuring the mass of a pure precipitate containing the analyte. There are two main types - precipitation and volatilization. For a successful analysis, the precipitate must be completely precipitated, of known composition, pure, and easily filtered. Factors like particle size, purity, and co-precipitation must be considered. The general steps involve preparing a solution, precipitating, filtering, washing, drying, and weighing the precipitate.
Gravimetric analysis determines the amount of analyte by measuring the mass of a precipitate. There are two main types - precipitation, where the analyte is converted to a solid precipitate, and volatilization, where the analyte or its decomposition products are volatilized. For successful gravimetric analysis, the precipitate must be pure, of known composition, and easily isolated by filtration and drying. Factors like temperature, concentration, and addition rate can influence precipitate particle size and purity.
This document discusses gravimetric analysis methods which involve weighing precipitates or volatile decomposition products. It describes two major types - precipitation methods where the analyte is converted to a precipitate, and volatilization methods where the analyte or its products are vaporized. Ideal precipitates are readily filtered, insoluble, stable, and of known composition. Larger particle sizes are easier to filter but particle size depends on factors like solubility, temperature and concentration. Precipitates can form by nucleation or growth, and experimental controls aim to produce crystalline rather than colloidal precipitates. Coprecipitation of impurities is also discussed.
Gravimetric analysis involves determining the amount of analyte by measuring the mass of a pure substance containing the analyte. It has two main types - precipitation and volatilization. In precipitation, the analyte is converted to a solid precipitate using a reagent, then the precipitate is filtered, washed, purified and weighed. In volatilization, the analyte or its products are vaporized and collected or the mass loss is measured. Key steps in gravimetric analysis include preparation of the analyte solution, precipitation, digestion, filtration, washing, drying/ignition, and weighing to calculate the analyte amount. It is potentially more accurate and precise than volumetric analysis but requires proper technique.
This document discusses complexometric titration, which involves titrating a metal ion with a complexing or chelating agent. It describes different types of complexometric titrations including direct titration, back titration, and replacement titration. It also discusses metal ion indicators, masking and demasking agents, and provides examples of standardizing EDTA and estimating magnesium sulfate and calcium gluconate through complexometric titration.
Introduction to Spectroscopy,
Introduction to UV, electronic transitions, terminology, chromophore, Auxochrome, Examples and Applications.
Introduction to IR, Fundamental vibrations, Types of Vibrations, Factors affecting the vibrational freaquencies, Group frequencies, examples and applications.
Gravimetric methods involve determining the mass of a pure compound related to the analyte. There are three main types: precipitation, volatilization, and electrogravimetry. Precipitation involves converting the analyte to a precipitate, filtering, washing, and weighing it. The precipitate must be pure, insoluble, stable, and of known composition. Particle size and properties affect filterability. Proper experimental control can optimize the precipitate for analysis.
Gravimetric analysis methods measure the mass of a substance. There are two types: precipitation and volatilization. Precipitation converts the analyte into an insoluble precipitate using a reagent. The precipitate is filtered, washed, dried and weighed. Volatilization converts the analyte or its decomposition products into a gas which is collected and weighed. An ideal precipitate is easily filtered, insoluble, stable, and has a known composition when dried or ignited. Particle size and purity affect filtration and washing effectiveness. Larger, crystalline particles are preferred over colloidal particles. Experimental conditions like temperature, concentration and mixing rate affect particle size and purity. Drying and ignition remove solvents and
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.
Gravimetric analysis determines the amount of analyte by measuring the mass of a precipitate. There are two main types - precipitation, where the analyte is converted to a solid precipitate, and volatilization, where the analyte or its decomposition products are volatilized. For successful gravimetric analysis, the precipitate must be pure, of known composition, and easily isolated by filtration and drying. Factors like temperature, concentration, and addition rate can influence precipitate particle size and purity.
This document discusses gravimetric analysis methods which involve weighing precipitates or volatile decomposition products. It describes two major types - precipitation methods where the analyte is converted to a precipitate, and volatilization methods where the analyte or its products are vaporized. Ideal precipitates are readily filtered, insoluble, stable, and of known composition. Larger particle sizes are easier to filter but particle size depends on factors like solubility, temperature and concentration. Precipitates can form by nucleation or growth, and experimental controls aim to produce crystalline rather than colloidal precipitates. Coprecipitation of impurities is also discussed.
Gravimetric analysis involves determining the amount of analyte by measuring the mass of a pure substance containing the analyte. It has two main types - precipitation and volatilization. In precipitation, the analyte is converted to a solid precipitate using a reagent, then the precipitate is filtered, washed, purified and weighed. In volatilization, the analyte or its products are vaporized and collected or the mass loss is measured. Key steps in gravimetric analysis include preparation of the analyte solution, precipitation, digestion, filtration, washing, drying/ignition, and weighing to calculate the analyte amount. It is potentially more accurate and precise than volumetric analysis but requires proper technique.
This document discusses complexometric titration, which involves titrating a metal ion with a complexing or chelating agent. It describes different types of complexometric titrations including direct titration, back titration, and replacement titration. It also discusses metal ion indicators, masking and demasking agents, and provides examples of standardizing EDTA and estimating magnesium sulfate and calcium gluconate through complexometric titration.
Introduction to Spectroscopy,
Introduction to UV, electronic transitions, terminology, chromophore, Auxochrome, Examples and Applications.
Introduction to IR, Fundamental vibrations, Types of Vibrations, Factors affecting the vibrational freaquencies, Group frequencies, examples and applications.
Gravimetric methods involve determining the mass of a pure compound related to the analyte. There are three main types: precipitation, volatilization, and electrogravimetry. Precipitation involves converting the analyte to a precipitate, filtering, washing, and weighing it. The precipitate must be pure, insoluble, stable, and of known composition. Particle size and properties affect filterability. Proper experimental control can optimize the precipitate for analysis.
Gravimetric analysis methods measure the mass of a substance. There are two types: precipitation and volatilization. Precipitation converts the analyte into an insoluble precipitate using a reagent. The precipitate is filtered, washed, dried and weighed. Volatilization converts the analyte or its decomposition products into a gas which is collected and weighed. An ideal precipitate is easily filtered, insoluble, stable, and has a known composition when dried or ignited. Particle size and purity affect filtration and washing effectiveness. Larger, crystalline particles are preferred over colloidal particles. Experimental conditions like temperature, concentration and mixing rate affect particle size and purity. Drying and ignition remove solvents and
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.
This document provides instructions for identifying cations through qualitative analysis using sodium hydroxide (NaOH) and ammonium hydroxide (NH3) solutions. Precipitates formed when salts are reacted with these reagents can indicate the present metal ions. Observations of solubility in excess reagent and reactions with other substances like hydrochloric acid help distinguish between ions. Proper technique like warming solutions gently and testing gas evolution with litmus paper is emphasized.
This document discusses the principles and procedures of conductometric analysis. Conductometric analysis measures the electrical conductivity of a solution due to ion mobility. The conductivity is affected by factors like number, charge, size of ions, and temperature. It involves titrating a solution containing ions and measuring the change in conductivity. This allows determination of the endpoint of the titration from the plotted conductivity-volume curve. The document defines key terms, describes instrumentation including conductivity cells and electrodes, and discusses different types of conductometric titrations like acid-base, redox, and complexometric titrations. Conductometric titrations provide accurate results for analyses without requiring indicators.
This document discusses complexometric titration, also known as chelatometry. It involves the titration of a metal ion with EDTA (ethylene diamine tetraacetic acid) to form a stable 1:1 metal-EDTA complex. EDTA is a hexadentate ligand that forms very stable complexes with metal ions. The titration is carried out under basic conditions to ensure the metal-EDTA complex forms. Various methods of complexometric titration are described such as direct titration, back titration, and replacement titration. Factors affecting the stability of metal-ligand complexes and requirements for metal ion indicators are also summarized.
Gas chromatography is a type of chromatography that uses a mobile gas phase to transport sample components through a column containing a stationary liquid or solid phase. The separation of components is based on their distribution between the mobile gas phase and stationary phase. There are two main types - gas-solid chromatography where the stationary phase is a solid, and gas-liquid chromatography where the stationary phase is a liquid coated on an inert solid support. Common applications of gas chromatography include separation and analysis of organic and inorganic compounds, study of reaction rates and mechanisms, and determination of molecular properties.
Polarography uses a dropping mercury electrode (DME) to measure the current flowing through an electrochemical cell as a function of the applied potential. A polarogram plots this current versus potential and provides qualitative and quantitative information about species undergoing oxidation or reduction reactions. Jaroslav Heyrovsky invented the polarographic method in 1922 and won the Nobel Prize for his contributions to electroanalytical chemistry. All modern voltammetric methods originate from polarography. The DME provides advantages like a reproducible surface area and the ability to form amalgams with metal ions.
1) Pericyclic reactions are single-step, concerted reactions that proceed through a cyclic transition state without intermediates.
2) They are classified as electrocyclic reactions, cycloaddition reactions, cheletropic reactions, sigmatropic rearrangements, or group transfer reactions depending on the type of bonding changes that occur.
3) Examples of pericyclic reactions include the Diels-Alder reaction, electrocyclic ring openings and closings, and the Claisen rearrangement.
This document provides an introduction to conductometric titrations. It explains that conductometric titrations measure the change in conductivity at the endpoint of a titration reaction. The document discusses the principles behind conductivity changes during titrations and the apparatus used. It then describes the procedure for conductometric titrations and plots the results. Finally, it provides examples of different types of conductometric titrations including neutralization, redox, and precipitation titrations.
Conductometry / conductometric titrationRabia Aziz
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
conductometric titration
This document provides an overview of acid-base titration and summarizes the key steps and considerations when performing a titration. It discusses selecting an appropriate indicator based on the relative strengths of the acid and base, performing multiple titrations to determine the endpoint accurately, and calculating pH at different points during the titration, including the initial pH, pH before and at the equivalence point, and pH after the equivalence point. Formulas are provided for calculating pH at these different stages of a titration, whether it involves a strong acid-strong base, strong acid-weak base, or weak acid-strong base reaction.
This document discusses polarography, which is a technique for analyzing solutions using two electrodes - a dropping mercury working electrode and a reference electrode. It provides details on:
1. How polarography works by applying a voltage to induce a redox reaction and measuring the resulting current.
2. The components needed, including the dropping mercury electrode, reference electrode, and a supporting electrolyte.
3. How polarograms are generated by plotting current vs. applied voltage and the different regions that can be seen on a polarogram.
4. Factors that influence the diffusion current measured, such as concentration of the analyte, diffusion coefficient, and drop lifetime. Equations for calculating diffusion current are also presented.
This document discusses conductometry, which is a method of analysis based on measuring the electrolytic conductance of a solution. It begins by classifying different electrochemical methods, including conductometry and electrophoresis which do not involve redox reactions. It then discusses key concepts in conductometry such as conductivity, conductance, equivalent conductance, and how various factors like ion nature, temperature, concentration, and electrode size affect conductance. It also provides examples of calculating conductance and equivalent conductance from experimental measurements. Instrumentation for conductometric determination includes a conductance cell and conductivity bridge.
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.
DYES part I ( intrduction, chromophore n auxochrome and classification.pptxDrAparanaDighade1
This document discusses the key properties and components of dyes. It defines chromophores as the part of a molecule responsible for its color, and notes that chromophores undergo π-π* or n-π* electronic transitions. Auxochromes are groups that intensify a dye's color by extending conjugation with the chromophore. Common auxochromes include -OH, -NH2, and -COOH groups. The document also classifies dyes based on their structure, application method, and presence of acidic or basic auxochrome groups.
Nucleophiles are negatively charged ions or molecules that donate an electron pair to form a new bond. Nucleophilicity refers to how readily a nucleophile can attack an electron deficient atom in a reaction like SN2. The strength of a nucleophile depends on factors like its charge, polarity, and steric hindrance. In polar protic solvents, nucleophilicity is determined more by polarity, while in polar aprotic solvents basicity is more important. Steric effects also influence nucleophilicity, as bulkier nucleophiles have more difficulty approaching the reaction site.
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.
Photo Diode as a Light sensor .Photo diode as an Electronic Device. V-I curve of Photo Diode.Advantage ,Disadvantage of Photodiode.Application of Photodiode.Types of Photodiode.
This powerpoint presentation will cover following aspects:
Kinds of Pericyclic Reactions and Brief details of their kinds
Molecular Orbitals and Orbitals Symmetry
Molecular Orbitals Description
Electrocyclic Reactions
Introduction to Dienes
Introduction to Dienophiles
Photochemical conditions
Ring Closure
Modes of Ring Closure
Diels- Alder Product recognition and Reversibility of Diels Alder Reaction
Conrotatory and Disrotatory arrangements
Cycloadditions in Complete Details
Dimerization , Frontier Orbitals Description, Endo Rule, Stereochemistry, Applications Hoffman's rule and a lot more……
The document summarizes the Dienone-Phenol rearrangement reaction. It begins by classifying rearrangement reactions based on the migrating group or atom. It then provides examples of the Dienone-Phenol rearrangement where disubstituted cyclohexadienones rearrange to the corresponding disubstituted phenols. The mechanism involves the generation of a carbocation through protonation, followed by rearrangement and loss of a proton to form the phenol product. The rearrangement is driven by aromatization. It notes applications in synthesizing anthracenes, phenanthrenes, and steroids like santonin. References on reaction mechanisms and rearrangements are also provided.
What is Gravimetric analysis, stepes invloved in gravimetry, Filteration medium in gravimetry, gravimetric factor, application, organic and inorganic prepecating agents
Gravimetric analysis methods determine the mass of a compound to quantify the analyte. Precipitation gravimetry is the most common method, where the analyte is precipitated from solution and the precipitate is filtered, dried, and weighed. Ideal precipitates are easily filtered, insoluble, and have a known composition. Factors like particle size, supersaturation, and electrolyte addition affect precipitation and coprecipitation. Other gravimetric methods include volatilization, where the analyte is converted to a known gas, electrogravimetry by electrodeposition, and thermogravimetry which measures mass changes with temperature.
This document provides instructions for identifying cations through qualitative analysis using sodium hydroxide (NaOH) and ammonium hydroxide (NH3) solutions. Precipitates formed when salts are reacted with these reagents can indicate the present metal ions. Observations of solubility in excess reagent and reactions with other substances like hydrochloric acid help distinguish between ions. Proper technique like warming solutions gently and testing gas evolution with litmus paper is emphasized.
This document discusses the principles and procedures of conductometric analysis. Conductometric analysis measures the electrical conductivity of a solution due to ion mobility. The conductivity is affected by factors like number, charge, size of ions, and temperature. It involves titrating a solution containing ions and measuring the change in conductivity. This allows determination of the endpoint of the titration from the plotted conductivity-volume curve. The document defines key terms, describes instrumentation including conductivity cells and electrodes, and discusses different types of conductometric titrations like acid-base, redox, and complexometric titrations. Conductometric titrations provide accurate results for analyses without requiring indicators.
This document discusses complexometric titration, also known as chelatometry. It involves the titration of a metal ion with EDTA (ethylene diamine tetraacetic acid) to form a stable 1:1 metal-EDTA complex. EDTA is a hexadentate ligand that forms very stable complexes with metal ions. The titration is carried out under basic conditions to ensure the metal-EDTA complex forms. Various methods of complexometric titration are described such as direct titration, back titration, and replacement titration. Factors affecting the stability of metal-ligand complexes and requirements for metal ion indicators are also summarized.
Gas chromatography is a type of chromatography that uses a mobile gas phase to transport sample components through a column containing a stationary liquid or solid phase. The separation of components is based on their distribution between the mobile gas phase and stationary phase. There are two main types - gas-solid chromatography where the stationary phase is a solid, and gas-liquid chromatography where the stationary phase is a liquid coated on an inert solid support. Common applications of gas chromatography include separation and analysis of organic and inorganic compounds, study of reaction rates and mechanisms, and determination of molecular properties.
Polarography uses a dropping mercury electrode (DME) to measure the current flowing through an electrochemical cell as a function of the applied potential. A polarogram plots this current versus potential and provides qualitative and quantitative information about species undergoing oxidation or reduction reactions. Jaroslav Heyrovsky invented the polarographic method in 1922 and won the Nobel Prize for his contributions to electroanalytical chemistry. All modern voltammetric methods originate from polarography. The DME provides advantages like a reproducible surface area and the ability to form amalgams with metal ions.
1) Pericyclic reactions are single-step, concerted reactions that proceed through a cyclic transition state without intermediates.
2) They are classified as electrocyclic reactions, cycloaddition reactions, cheletropic reactions, sigmatropic rearrangements, or group transfer reactions depending on the type of bonding changes that occur.
3) Examples of pericyclic reactions include the Diels-Alder reaction, electrocyclic ring openings and closings, and the Claisen rearrangement.
This document provides an introduction to conductometric titrations. It explains that conductometric titrations measure the change in conductivity at the endpoint of a titration reaction. The document discusses the principles behind conductivity changes during titrations and the apparatus used. It then describes the procedure for conductometric titrations and plots the results. Finally, it provides examples of different types of conductometric titrations including neutralization, redox, and precipitation titrations.
Conductometry / conductometric titrationRabia Aziz
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
conductometric titration
This document provides an overview of acid-base titration and summarizes the key steps and considerations when performing a titration. It discusses selecting an appropriate indicator based on the relative strengths of the acid and base, performing multiple titrations to determine the endpoint accurately, and calculating pH at different points during the titration, including the initial pH, pH before and at the equivalence point, and pH after the equivalence point. Formulas are provided for calculating pH at these different stages of a titration, whether it involves a strong acid-strong base, strong acid-weak base, or weak acid-strong base reaction.
This document discusses polarography, which is a technique for analyzing solutions using two electrodes - a dropping mercury working electrode and a reference electrode. It provides details on:
1. How polarography works by applying a voltage to induce a redox reaction and measuring the resulting current.
2. The components needed, including the dropping mercury electrode, reference electrode, and a supporting electrolyte.
3. How polarograms are generated by plotting current vs. applied voltage and the different regions that can be seen on a polarogram.
4. Factors that influence the diffusion current measured, such as concentration of the analyte, diffusion coefficient, and drop lifetime. Equations for calculating diffusion current are also presented.
This document discusses conductometry, which is a method of analysis based on measuring the electrolytic conductance of a solution. It begins by classifying different electrochemical methods, including conductometry and electrophoresis which do not involve redox reactions. It then discusses key concepts in conductometry such as conductivity, conductance, equivalent conductance, and how various factors like ion nature, temperature, concentration, and electrode size affect conductance. It also provides examples of calculating conductance and equivalent conductance from experimental measurements. Instrumentation for conductometric determination includes a conductance cell and conductivity bridge.
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.
DYES part I ( intrduction, chromophore n auxochrome and classification.pptxDrAparanaDighade1
This document discusses the key properties and components of dyes. It defines chromophores as the part of a molecule responsible for its color, and notes that chromophores undergo π-π* or n-π* electronic transitions. Auxochromes are groups that intensify a dye's color by extending conjugation with the chromophore. Common auxochromes include -OH, -NH2, and -COOH groups. The document also classifies dyes based on their structure, application method, and presence of acidic or basic auxochrome groups.
Nucleophiles are negatively charged ions or molecules that donate an electron pair to form a new bond. Nucleophilicity refers to how readily a nucleophile can attack an electron deficient atom in a reaction like SN2. The strength of a nucleophile depends on factors like its charge, polarity, and steric hindrance. In polar protic solvents, nucleophilicity is determined more by polarity, while in polar aprotic solvents basicity is more important. Steric effects also influence nucleophilicity, as bulkier nucleophiles have more difficulty approaching the reaction site.
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.
Photo Diode as a Light sensor .Photo diode as an Electronic Device. V-I curve of Photo Diode.Advantage ,Disadvantage of Photodiode.Application of Photodiode.Types of Photodiode.
This powerpoint presentation will cover following aspects:
Kinds of Pericyclic Reactions and Brief details of their kinds
Molecular Orbitals and Orbitals Symmetry
Molecular Orbitals Description
Electrocyclic Reactions
Introduction to Dienes
Introduction to Dienophiles
Photochemical conditions
Ring Closure
Modes of Ring Closure
Diels- Alder Product recognition and Reversibility of Diels Alder Reaction
Conrotatory and Disrotatory arrangements
Cycloadditions in Complete Details
Dimerization , Frontier Orbitals Description, Endo Rule, Stereochemistry, Applications Hoffman's rule and a lot more……
The document summarizes the Dienone-Phenol rearrangement reaction. It begins by classifying rearrangement reactions based on the migrating group or atom. It then provides examples of the Dienone-Phenol rearrangement where disubstituted cyclohexadienones rearrange to the corresponding disubstituted phenols. The mechanism involves the generation of a carbocation through protonation, followed by rearrangement and loss of a proton to form the phenol product. The rearrangement is driven by aromatization. It notes applications in synthesizing anthracenes, phenanthrenes, and steroids like santonin. References on reaction mechanisms and rearrangements are also provided.
What is Gravimetric analysis, stepes invloved in gravimetry, Filteration medium in gravimetry, gravimetric factor, application, organic and inorganic prepecating agents
Gravimetric analysis methods determine the mass of a compound to quantify the analyte. Precipitation gravimetry is the most common method, where the analyte is precipitated from solution and the precipitate is filtered, dried, and weighed. Ideal precipitates are easily filtered, insoluble, and have a known composition. Factors like particle size, supersaturation, and electrolyte addition affect precipitation and coprecipitation. Other gravimetric methods include volatilization, where the analyte is converted to a known gas, electrogravimetry by electrodeposition, and thermogravimetry which measures mass changes with temperature.
This document discusses gravimetric analysis methods which involve weighing precipitates or volatile decomposition products. It describes two major types - precipitation methods where the analyte is converted to a precipitate, and volatilization methods where the analyte or its products are vaporized. Ideal precipitates are readily filtered, insoluble, stable, and of known composition. Larger particle sizes are easier to filter but particle size depends on factors like solubility, temperature and concentration. Precipitates can form by nucleation or growth, and experimental controls aim to produce crystalline rather than colloidal precipitates. Coprecipitation of impurities is also discussed.
This document discusses gravimetric analysis, which is a quantitative analytical technique where the amount of analyte is determined by measuring its mass. There are several types of gravimetric methods including precipitation gravimetry, where the analyte is separated as a precipitate and weighed. An ideal precipitate would be easily filtered, insoluble, and of known composition when dried or ignited. The document outlines the general procedure for precipitation gravimetry and factors that influence precipitate formation and particle size such as supersaturation and coagulation of colloids.
Gravimetry.pptx gravimetry techniques and applicationMrUnknown593882
Gravimetric analysis is a quantitative analytical technique based on weighing a precipitate to determine the amount of analyte present. Key steps include dissolving the sample, adding excess precipitating reagent to form an insoluble precipitate, filtering and washing the precipitate, drying and weighing the precipitate. Factors such as precipitation rate and particle size affect purity and accuracy. By controlling variables like temperature, reagent addition rate, and supersaturation, large pure crystals can be obtained for accurate gravimetric analysis.
Gravimetric analysis is a quantitative analytical method where the amount of analyte is determined by measuring the mass of a pure substance. It involves converting the analyte into a solid precipitate through precipitation, volatilization, electrolysis, or thermogravimetry. The precipitate is then filtered, washed to remove impurities, dried, and weighed. Key steps include preparing the sample solution, precipitating the analyte, digesting and filtering the precipitate, washing to remove trapped impurities, drying or igniting, and calculating the mass of analyte based on the final weighted form. Conditions like supersaturation, particle size, and washing solutions must be carefully controlled to obtain accurate and precise results.
This document provides an overview of gravimetric analysis. It discusses that gravimetric analysis involves selectively converting the analyte to an insoluble form, filtering and weighing the precipitate. The summary describes the key steps as:
1) Precipitation of the analyte to form a solid precipitate
2) Filtering and washing the precipitate
3) Drying or igniting the precipitate to convert it to a known chemical form for accurate weighing
4) Weighing the precipitate to calculate the amount of analyte based on its chemical composition
This document discusses the principles and techniques of gravimetric analysis. Gravimetry involves measuring mass or mass changes to determine the quantity of an analyte. Key points include:
Precipitation gravimetry forms an insoluble compound upon addition of a precipitating reagent. The precipitate must be pure with no impurities. Volatilization gravimetry measures mass loss upon vaporization of a volatile component. Particulate gravimetry separates and weighs analytes using filtration or extraction. Proper technique aims to produce pure, contaminant-free precipitates for accurate gravimetric determination.
Gravimetric analysis involves quantitatively analyzing a sample by selectively converting the analyte into an insoluble precipitate, isolating the precipitate, drying and weighing it, and using the mass to calculate the original amount of analyte. The key steps are precipitation of the analyte, filtration to isolate the precipitate, drying or ignition to remove water and obtain a stable form, and weighing to determine the mass and calculate the amount of analyte based on the chemical composition of the precipitate. Factors such as the solubility, purity, and crystal size of the precipitate affect the accuracy and precision of the analysis.
The document discusses the history and techniques of gravimetric analysis. It provides background on influential chemists like Berzelius and Richards who developed many gravimetric analysis methods in the 19th century. The document then explains key concepts in gravimetric analysis like accuracy vs precision. It outlines the common steps involved in gravimetric analysis including precipitation, filtration, drying and weighing. Finally, it discusses important factors that influence precipitation like particle size, digestion, and conditions for analytical precipitation.
Gravimetric analysis involves converting the analyte of interest into an insoluble compound and weighing it. This document discusses the gravimetric estimation of barium. A measured volume of the barium chloride solution is treated with sulfuric acid to precipitate barium sulfate. The precipitate is filtered, dried, and weighed. The mass of barium sulfate is used to calculate the mass of barium in the original solution, based on the fact that 233.36 g of barium sulfate contains 137.36 g of barium.
This document discusses the principles and methods of gravimetric analysis. Gravimetric analysis involves isolating an element or compound and weighing it to determine the amount present. Key points covered include:
- Precipitation is the most common separation method and involves precipitating the analyte as an insoluble compound that can be isolated by filtration and weighed.
- Factors that influence precipitation such as supersaturation, nucleation, crystal growth, and co-precipitation are explained.
- Methods for purifying and washing precipitates to remove impurities are outlined.
- Specific examples of gravimetric determinations for chloride, sulfate, aluminum, and nickel are mentioned.
This document provides information on gravimetric analysis including theory, apparatus, chemicals, procedures, calculations, and common gravimetric techniques. Gravimetric analysis involves isolating the analyte as a precipitate through a chemical reaction, filtering and washing the precipitate, drying or igniting it, and weighing it to calculate the mass of analyte present. Key steps include precipitation, digestion, filtration, washing, drying or igniting the precipitate, and performing calculations based on the chemical reaction and weights. Common gravimetric techniques described include determination of lead using precipitation with chloride and calculations based on the precipitate weight.
This document discusses the classification and preparation of colloidal dispersions. It begins by classifying colloids based on the interaction between the dispersed phase and dispersion medium into lyophilic, lyophobic, and association colloids. Lyophilic colloids have affinity for the dispersion medium, making them thermodynamically stable. Lyophobic colloids require special preparation methods since the dispersed particles are solvent-hating. Association colloids involve micelle formation using surfactants above the critical micelle concentration. The document also describes various methods for preparing and purifying colloidal dispersions, including mechanical grinding, peptization, addition of nonsolvents, and ultrafiltration.
This document discusses gravimetric analysis methods. It defines gravimetric analysis as isolating and weighing an element or compound in pure form to determine the quantity present. The main types discussed are precipitation gravimetry, electrogravimetry, and volatilization gravimetry. Precipitation gravimetry, the formation of an insoluble precipitate, is explained in detail including factors that influence successful precipitation and purity of the precipitate. Advantages include high precision and accuracy, while disadvantages include being time-consuming and requiring clean glassware and accurate weighing. An example of barium chloride estimation by precipitating and weighing barium sulfate is also provided.
This document provides an overview of crystallization as a separation and purification technique. It discusses key concepts such as crystallization, nucleation, crystal growth, and factors that affect crystallization. Specifically, it describes three steps of crystallization from solution: induction of supersaturation through methods like cooling, solvent evaporation, or adiabatic evaporation; nucleation through Miers' theory; and crystal growth which depends on concentration, temperature, and velocity gradients. It also discusses methods of controlling crystal size and factors that influence the crystallization process like temperature, impurities, and agitation.
Chapter 6 Gravimetric Analysis Al modi-1 - Copy.pptbirhanhailie
Gravimetric analysis is a quantitative analytical method to determine the amount of a substance by measuring its mass. It involves converting the analyte into a new substance, precipitate, or volatile form so its mass can be easily measured. The key steps are: (1) precipitating or converting the analyte into a solid form, (2) filtering to separate the solid product, (3) drying and weighing the product, and (4) calculating the mass of analyte based on the precipitate's mass and stoichiometric relationships. Gravimetric analysis provides highly accurate results when performed properly by skilled analysts.
The various stages of processing that occur after the completion of the fermentation or bioconversion stage, including separation, purification, and packaging of the product
This document provides an overview of physio-chemical processes including precipitation, ignition, distillation, vaporization, evaporation, and others. It discusses these processes in detail, providing definitions, examples, and applications. Specifically, it discusses precipitation reactions and how insoluble solids are formed, defines ignition as strongly heating an organic substance until only inorganic residue remains, and describes different types of distillation like simple, fractional, and steam distillation used to separate liquid mixtures.
Episode 44 : 4 Stages Of Solid Liquid Separations
Cost of S/L relates directly to the volume of material
Pressurized equipment is more expensive to operate than thickener
Other techniques are classified according to the substances that act upon, namely the liquid, the solid particles, solids concentration and solid-liquid interaction
SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
Asthma is a chronic inflammatory lung disease that causes narrowing of the airways. It affects over 300 million people worldwide. The hallmark symptoms of asthma include wheezing, coughing, chest tightness, and shortness of breath. Asthma is caused by a combination of genetic and environmental factors that lead to airway inflammation and constriction. Common triggers include allergens, viruses, exercise, and air pollution. Diagnosis involves lung function tests to measure airflow limitation and its improvement with bronchodilator medication. Treatment focuses on reducing symptoms with bronchodilators and preventing exacerbations with anti-inflammatory drugs like corticosteroids.
Asthma is a chronic disease characterized by inflammation of the airways causing coughing, wheezing, chest tightness, and difficulty breathing. It is usually caused by allergic triggers like pollen, dust mites, or animal dander that lead to bronchospasms and airway obstruction. Diagnosis involves patient history, physical exam, pulmonary function tests, and allergy testing. Treatment includes bronchodilators, corticosteroids, leukotriene modifiers, and monoclonal antibodies to reduce inflammation and prevent symptoms.
Ischaemic heart disease is caused by an imbalance between the heart's supply and demand for oxygenated blood, usually due to atherosclerosis narrowing the coronary arteries. The main symptoms are chest pain or discomfort known as angina. There are different types of angina that vary based on their triggers and patterns. Diagnosis involves tests like ECG, echocardiogram, stress tests and angiography. Treatment options include medications to reduce demands on the heart like nitrates, beta-blockers, and calcium channel blockers, as well as interventions like angioplasty, stents and bypass surgery.
Atherosclerosis is a disease where plaque builds up in the arteries. Over time, the plaque hardens and narrows the arteries, limiting blood flow. Risk factors include age, family history, smoking, high blood pressure, high cholesterol, diabetes, and obesity. Complications arise when blood flow is reduced to organs like the heart, brain, kidneys, and limbs, potentially causing heart attacks, strokes, chronic kidney disease, or poor circulation. Treatment focuses on lifestyle changes and medications to control risk factors and symptoms.
This document provides an outline for a lecture on hypertension. It begins with objectives to understand hypertension's etiology, risk factors, and complications. It then covers definitions of hypertension, classifications based on cause and clinical features, risk factors, pathogenesis, regulation of blood pressure, vascular changes in hypertension, and complications affecting the heart, blood vessels, kidneys, eyes, and brain. The lecture topics include primary and secondary causes, benign vs malignant hypertension, endocrine factors influencing blood pressure, and target organ damage.
Hypertension and its pathophysiology.pptxImtiyaz60
The document discusses hypertension and the heart. It provides details on:
- The structure and layers of the heart, including the myocardium and pericardium.
- The path of blood through the heart, from the vena cava and atria to the ventricles, valves, and out the aorta to the body.
- Additional details are given on heart size, location in the thoracic cavity, and the double-walled pericardium surrounding and protecting the heart.
This document discusses various appetite stimulants, digestants, and carminatives. It describes how appetite is influenced by several factors in the hypothalamus and gut-brain pathways. Common appetite stimulants mentioned include lemon pickles, bitter orange peel, and soups containing aromatic oils. Some medications can increase appetite but also have side effects. The document also discusses various digestive enzymes and bile acids that may aid digestion, though evidence for their efficacy is limited. Finally, it outlines several common carminative herbs and spices that can relieve gas and bloating.
Anti Ulcer drugs pharmacology and classificationImtiyaz60
This document summarizes drugs used to treat peptic ulcers. It discusses the anatomy and physiology of gastric acid secretion regulated by histamine, acetylcholine, and gastrin. It describes prostaglandins' protective role in the stomach and how H2 receptor blockers and proton pump inhibitors work to suppress acid secretion. H2 blockers competitively inhibit histamine receptors, while PPIs irreversibly inactivate the proton pump. Common medications discussed include cimetidine, ranitidine, famotidine, omeprazole, and lansoprazole. The goals of anti-ulcer therapy are relieving pain, promoting healing, and preventing complications and relapse.
Ginger and asafoetida are plants with medicinal properties. Ginger is native to Southeast Asia and cultivated in many tropical regions. It has buff-colored rhizomes with an aromatic odor and taste. Chemical constituents include volatile oils and phenolic compounds that give ginger its flavor and pharmacological effects. Asafoetida is an oleo-gum-resin obtained from Ferula plants. It occurs in tear or mass forms, has an intense odor, and chemical tests detect umbelliferone. Both ginger and asafoetida have traditional uses as carminatives, expectorants, and to treat conditions like nausea, flatulence, and asthma. They can be subject to adulteration
Leprosy is caused by Mycobacterium leprae. It primarily affects the skin and peripheral nerves, causing hypopigmented patches and thickening of nerves. There are two main forms - tuberculoid leprosy, which causes localized lesions, and lepromatous leprosy, which involves multiple organs. Diagnosis involves skin smears and biopsies to identify acid-fast bacilli. Treatment involves multidrug chemotherapy regimens containing dapsone, rifampicin, and clofazimine. Prevention focuses on contact tracing, chemoprophylaxis, isolation during reactions, and rehabilitation.
Tuberculosis (TB) is a chronic bacterial infection caused by Mycobacterium tuberculosis that typically forms granulomas in the lungs. It is treatable with a combination of anti-TB drugs over a 6-12 month period to kill both actively replicating and dormant bacilli. Diagnosis involves physical exam, chest x-ray, tuberculin skin test, and sputum culture. Risk factors include HIV infection, poverty, and crowded living conditions.
Stroke is the 5th leading cause of death in the US. There are three main types of stroke: ischemic, hemorrhagic, and transient ischemic attacks (TIAs). Ischemic strokes, which account for 85% of cases, occur when a blood clot blocks an artery supplying blood to the brain. Hemorrhagic strokes occur when a brain artery ruptures due to conditions like hypertension. TIAs are temporary and cause no permanent damage but indicate risk for future strokes. Symptoms of stroke appear suddenly and include face drooping, arm weakness, speech difficulties, and severe headache. Diagnostic tests help determine the type and location of stroke. Lifestyle changes and medical treatment can help prevent strokes.
The thyroid gland is located in the neck below the larynx. It produces thyroid hormones including thyroxine (T4) and triiodothyronine (T3) which increase metabolism in nearly every organ system. Iodine is necessary for thyroid hormone production. Disorders include hypothyroidism, where thyroid hormone production is inadequate, and hyperthyroidism, where production is excessive. Graves' disease is an autoimmune cause of hyperthyroidism. Cretinism results from untreated congenital hypothyroidism and causes severe physical and mental impairment.
Inflammatory bowel disease (IBD) represents a group of chronic disorders that cause prolonged inflammation of the digestive tract. The two main types are ulcerative colitis, which causes inflammation and ulcers in the lining of the large intestine, and Crohn's disease, which is a chronic inflammatory disease that can affect any part of the gastrointestinal tract from mouth to anus. IBD is treated through a combination of medications, dietary changes, and sometimes surgery, with the goals of inducing and maintaining remission of symptoms, preventing complications, and avoiding surgery if possible. Treatments include aminosalicylates, corticosteroids, immunosuppressants, biologics that target tumor necrosis factor, and antimicrobial agents.
Tannins are polyphenolic compounds found in many plants. They are classified as hydrolysable tannins, condensed tannins, or pseudo-tannins. Hydrolysable tannins are hydrolyzed by acids into gallic acid or ellagic acid, while condensed tannins are more resistant to hydrolysis. Tannins are extracted using mixtures of polar and non-polar solvents due to their high molecular weight. Identification tests for tannins include the gelatin test, Goldbeater's skin test, and reactions with ferrous sulfate or ferric chloride that produce colors. Pterocarpus marsupium, or Bijasal, is a plant source of k
This document discusses various drug classes used in the treatment of heart failure, including their mechanisms and effects. Diuretics reduce preload on the heart by reducing extracellular fluid volume through natriuresis. Vasodilators such as nitroglycerin and ACE inhibitors reduce preload and afterload by dilating blood vessels. Nesiritide is a natriuretic peptide that causes vasodilation and natriuresis. β-blockers improve outcomes in heart failure by inhibiting the deleterious effects of sympathetic activation on the heart.
Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis that most commonly infects the lungs. It can be treated with antibiotics. TB is spread through airborne droplets when an infected person coughs or sneezes. While latent TB means the immune system has contained the infection and the person is not infectious, active TB means the person is sick and can spread the disease. Standard TB treatment involves a combination of antibiotics like isoniazid, rifampin and ethambutol over a period of 6-9 months.
The document discusses infectious diseases and infectious agents. It covers host barriers to infection like the skin, respiratory system, gastrointestinal tract, and urogenital tract. It describes how these barriers can fail and allow infection. It also discusses the different classes of infectious agents including bacteria, viruses, fungi and parasites. The document outlines the different types of inflammatory responses infections can cause like suppurative inflammation, granulomatous inflammation, and cytopathic responses. It covers how microbes can evade the immune system and the various ways infections can be transmitted.
The document defines key terms related to the electrophysiology of the heart such as action potential, membrane potential, refractory period, and threshold potential. It then describes the four phases of the cardiac action potential: Phase 0 involves stimulation and sodium/calcium influx causing depolarization; Phase 1 involves partial repolarization through ion efflux; Phase 2 involves a plateau phase through continued ion fluxes; Phase 3 involves full repolarization through ion efflux slower than depolarization. Phase 4 is the interval between repolarizations. The cardiac action potential triggers mechanical contraction. An electrocardiogram detects and records the summed action potentials to analyze patterns like the P, QRS, and T waves related to atrial depolarization, ventricular depolarization
How to Manage Reception Report in Odoo 17Celine George
A business may deal with both sales and purchases occasionally. They buy things from vendors and then sell them to their customers. Such dealings can be confusing at times. Because multiple clients may inquire about the same product at the same time, after purchasing those products, customers must be assigned to them. Odoo has a tool called Reception Report that can be used to complete this assignment. By enabling this, a reception report comes automatically after confirming a receipt, from which we can assign products to orders.
Elevate Your Nonprofit's Online Presence_ A Guide to Effective SEO Strategies...TechSoup
Whether you're new to SEO or looking to refine your existing strategies, this webinar will provide you with actionable insights and practical tips to elevate your nonprofit's online presence.
Information and Communication Technology in EducationMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 2)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐈𝐂𝐓 𝐢𝐧 𝐞𝐝𝐮𝐜𝐚𝐭𝐢𝐨𝐧:
Students will be able to explain the role and impact of Information and Communication Technology (ICT) in education. They will understand how ICT tools, such as computers, the internet, and educational software, enhance learning and teaching processes. By exploring various ICT applications, students will recognize how these technologies facilitate access to information, improve communication, support collaboration, and enable personalized learning experiences.
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐫𝐞𝐥𝐢𝐚𝐛𝐥𝐞 𝐬𝐨𝐮𝐫𝐜𝐞𝐬 𝐨𝐧 𝐭𝐡𝐞 𝐢𝐧𝐭𝐞𝐫𝐧𝐞𝐭:
-Students will be able to discuss what constitutes reliable sources on the internet. They will learn to identify key characteristics of trustworthy information, such as credibility, accuracy, and authority. By examining different types of online sources, students will develop skills to evaluate the reliability of websites and content, ensuring they can distinguish between reputable information and misinformation.
Philippine Edukasyong Pantahanan at Pangkabuhayan (EPP) CurriculumMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐄𝐏𝐏 𝐂𝐮𝐫𝐫𝐢𝐜𝐮𝐥𝐮𝐦 𝐢𝐧 𝐭𝐡𝐞 𝐏𝐡𝐢𝐥𝐢𝐩𝐩𝐢𝐧𝐞𝐬:
- Understand the goals and objectives of the Edukasyong Pantahanan at Pangkabuhayan (EPP) curriculum, recognizing its importance in fostering practical life skills and values among students. Students will also be able to identify the key components and subjects covered, such as agriculture, home economics, industrial arts, and information and communication technology.
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐍𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐒𝐜𝐨𝐩𝐞 𝐨𝐟 𝐚𝐧 𝐄𝐧𝐭𝐫𝐞𝐩𝐫𝐞𝐧𝐞𝐮𝐫:
-Define entrepreneurship, distinguishing it from general business activities by emphasizing its focus on innovation, risk-taking, and value creation. Students will describe the characteristics and traits of successful entrepreneurs, including their roles and responsibilities, and discuss the broader economic and social impacts of entrepreneurial activities on both local and global scales.
Gender and Mental Health - Counselling and Family Therapy Applications and In...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
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How to Download & Install Module From the Odoo App Store in Odoo 17Celine George
Custom modules offer the flexibility to extend Odoo's capabilities, address unique requirements, and optimize workflows to align seamlessly with your organization's processes. By leveraging custom modules, businesses can unlock greater efficiency, productivity, and innovation, empowering them to stay competitive in today's dynamic market landscape. In this tutorial, we'll guide you step by step on how to easily download and install modules from the Odoo App Store.
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إضغ بين إيديكم من أقوى الملازم التي صممتها
ملزمة تشريح الجهاز الهيكلي (نظري 3)
💀💀💀💀💀💀💀💀💀💀
تتميز هذهِ الملزمة بعِدة مُميزات :
1- مُترجمة ترجمة تُناسب جميع المستويات
2- تحتوي على 78 رسم توضيحي لكل كلمة موجودة بالملزمة (لكل كلمة !!!!)
#فهم_ماكو_درخ
3- دقة الكتابة والصور عالية جداً جداً جداً
4- هُنالك بعض المعلومات تم توضيحها بشكل تفصيلي جداً (تُعتبر لدى الطالب أو الطالبة بإنها معلومات مُبهمة ومع ذلك تم توضيح هذهِ المعلومات المُبهمة بشكل تفصيلي جداً
5- الملزمة تشرح نفسها ب نفسها بس تكلك تعال اقراني
6- تحتوي الملزمة في اول سلايد على خارطة تتضمن جميع تفرُعات معلومات الجهاز الهيكلي المذكورة في هذهِ الملزمة
واخيراً هذهِ الملزمة حلالٌ عليكم وإتمنى منكم إن تدعولي بالخير والصحة والعافية فقط
كل التوفيق زملائي وزميلاتي ، زميلكم محمد الذهبي 💊💊
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Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
2. 2
Points to be covered
• Principle and steps involved in gravimetric
analysis.
• Purity of the precipitate: co-precipitation and
post precipitation,
• Estimation of barium sulphate
3. 3
Introduction
• Gravimetric Analysis is a group of analytical methods in which
the amount of analyte is determined by the measurement of the
mass of a pure substance containing the analyte.
Types of Gravimetric Analyses:
• There are two main types of gravimetric analyses:
A) Precipitation
– analyte must first be converted to a solid (precipitate) by
precipitation with an appropriate reagent.
– The precipitates from solution is filtered, washed, purified
(if necessary) and weighed.
B) Volatilization
– In this method the analyte or its decomposition products
are volatilised (dried) and then collected and weighed, or
alternatively, the mass of the volatilised product is
determined indirectly by the loss of mass of the sample.
4. 11/1/2018 Deokate U A 4
Criteria For a successful determination
• For a successful determination in gravimetric analysis the
following criteria should be met
1. The desired substance must be completely precipitated. In
most determination the precipitate is of such low
solubility that losses from dissolution are negligible. An
additional factor is the common ion effect, this further
decrease the solubility of the precipitate.
– E.g. When Ag+ is precipitated out by addition of Cl-
– Ag+ + Cl- = AgCl
• The low solubility of AgCl is reduced further by the excess
of Cl- which is added force to the reaction to proceed
towards right side.
5. 11/1/2018 Deokate U A 5
Criteria For a successful determination
2. The weighed form of the product should be of
known composition.
3. The product should be pure and easily filtered.
4. Easy in handling i.e. ppt filtering, washing drying
and weighing.
• It is usually difficult to obtain a product which is
pure or which is free from impurities.
• This could be reduced by careful precipitation
and sufficient washing.
6. 11/1/2018 Deokate U A 6
Advantages of Gravimetric Analysis
• Accurate and precise: Gravimetric analysis is
potentially more accurate and more precise than
volumetric analysis
• Possible sources of errors can be checked:
Gravimetric analysis avoids problems with
temperature fluctuations, calibration errors, and
other problems associated with volumetric
analysis.
• It is an ABSOLUTE method.
• Relatively inexpensive
7. 11/1/2018 Deokate U A 7
Disadvantages
• But there are potential problems with
gravimetric analysis that must be avoided to
get good results.
• Proper lab technique is critical
• Careful and time consuming.
• Scrupulously clean glassware.
• Very accurate weighing.
• Coprecipitation.
8. 11/1/2018 Deokate U A 8
Properties of precipitate
• The ppt should be so insoluble that no significant
loss occurs during filtration and washing
• Physical nature of ppt should be such that it cab
be easily separated by filtration
• The PPT should be stable to atmospheric condn.
• The ppt must be convertible to pure compound of
definite composition, either by ignition or by
simple chemical operations such as evaporations.
• Have large crystals (Easier to filter large crystals)
• Be free of contaminants
9. 11/1/2018 Deokate U A 9
Particle Size and Filterability of
Precipitates
• Precipitates made up of large particles are
generally desirable in gravimetric work
because large particles are easy to filter and
wash free of impurities. In addition, such
precipitates are usually purer than are
precipitates made up of fine particles.
• Three types of ppt are produced
– Crystalline, Curdy and gelatinous etc.
10. 11/1/2018 Deokate U A 10
Process of precipitation
• It is a most imp step in gravimetric analysis
• Involves both physical and chemical process
• The physical process consists of three steps
1) Super saturation: the solution phase contains more dissolved salt than at
equilibrium. The driving force will be for the system to approach
equilibrium (saturation).
2) Nucleation : initial phase of precipitation. A min number of particle will
gather together to form a nucleus of particle or precipitate (solid phase).
Higher degree of super saturation, the greater rate of nucleation
• nucleation involves the formation of ion pairs and finally a group of ions
formed.
• it is of two types 1. Spontaneous and 2. Induced
3) Crystal growth : particle enlargement process. Nucleus will grow by
deposition of particles precipitate onto the nucleus and forming a crystal
of a specific geometric shape. Involving two steps diffusion of ion to
surface of nucleus and Deposition on surface.
11. 11/1/2018 Deokate U A 11
Precipitation process (Von weimarn eq)
• Von weimarn discover – the particle size of precipitates is
inversely proportional to the relative supersaturation of the sol.
during the precipitation process.
– The von Weimarn Ratio (The lower the better)
– von Weimarn ratio = (Q – S)/S
• A measure of relative supersaturation or supersaturation ratio
• If high, get excessive nucleation, lots of small crystals, large
surface area
• If low, get larger, fewer crystals, small surface area
• S = solubility of precipitate at equilibrium, ( Keep it high with
high temperatures, adjusting pH)
• Q = concentration of reagents before precipitation (Keep it low
by using dilute solutions, stir mixture well, add reactants slowly)
• Can lower S later by cooling mixture after crystals have formed
12. What Factors Determine Particle Size?
The particle size of solids formed by precipitation
varies enormously. At one extreme are colloidal
suspension, whose tiny particles are invisible to
the naked eye (10-7 to 10-4 cm in diameter).
Colloidal particles show no tendency to settle
from solution, nor are they easily filtered. At the
other extreme are particles with dimensions on
the order of tenths of millimeter or greater. The
temporary dispersion of such particles in the
liquid phase is called a crystalline suspension. The
particles of a crystalline suspension tend to settle
s1
p
1/1
o
/20
n
18 taneously and areDr
eoe
kata
e Ud
A ily filtered. 15
13. 11/1/2018 Deokate U A 13
The particle size of a precipitate is influenced by
experimental variables as precipitate solubility,
temperature, reactant concentrations, and the
rate at which reactants are mixed. The particle size
is related to a single property of the system called
its relative supersaturation, where
relative supersaturation = (Q – S) / S
In this equation, Q is the concentration of the
solute at any instant and S is its equilibrium
solubility.
When (Q – S)/ S is large, the precipitate tends to
be colloidal.
when (Q – S) / S is small, a crystalline solid is more
likely.
14. 11/1/2018 Deokate U A 14
• How do Precipitates Form? Precipitates form in two
ways, by nucleation and by particle growth. The
particle size of a freshly formed precipitate is
determined by which way is faster.
In nucleation, a few ions, atoms, or molecules
(perhaps as few as four or five) come together to form
a stable solid. Often, these nuclei form on the surface
of suspended solid contaminants, such as dust
particles. Further precipitation then involves a
competition between additional nucleation and
growth on existing nuclei (particle growth). If
nucleation predominates, a precipitate containing a
large number of small particles results; if growth
predominates, a smaller number of larger particles is
produced.
15. 11/1/2018 Deokate U A 15
Controlling Particle Size
variables
Experimental
supersaturation and thus
that minimize
lead to crystalline
precipitates include elevated
increase the solubility of the precipitate (S
temperatures to
in
Equation), dilute solutions (to minimize Q), and
slow addition of the precipitating agent with good
stirring. The last two measures also minimize the
concentration of the solute (Q) at any given instant.
Larger particles can also be obtained by pH control,
provided the solubility of the precipitate depends
on pH.
16. 11/1/2018 Deokate U A 16
Colloidal Precipitates
Coagulation
hastened by heating, stirring, and adding
of Colloids: Coagulation can be
an
electrolyte to the medium.
Colloidal suspensions are stable because all the
particles present are either positively or negatively
charged. This charge results from cations or anions
that are bound to the surface of the particles. The
process by which ions are retained on the surface
of a solid is known as adsorption. We can readily
demonstrate that colloidal particles are charged
by observing their migration when placed in an
electrical field.
18. Peptization of Colloids
Peptization refers to the process by which a
coagulated colloid reverts to its original dispersed
state. When a coagulated colloid is washed, some
of the electrolyte responsible for its coagulation is
leached from the internal liquid in contact with
the solid particles. Removal of this electrolyte has
the effect of increasing the volume of the counter-
ion layer. The repulsive forces responsible for the
original colloidal state are then reestablished, and
particles detach themselves from the coagulated
mass. The washings become cloudy as the freshly
d
11
i/s
1/p
201e
8 rsed particles pass
Deot
kah
te U
rA
ough the filter
. 21
19. 11/1/2018 Deokate U A 19
Crystalline Precipitates
Crystalline precipitates are generally more easily filtered
and purified than coagulated colloids. In addition, the size
of individual crystalline particles, and thus their
filterability, can be controlled to a degree.
The particle size of crystalline solids can often be
improved significantly by minimizing Q, maximizing S, or
both in Equation. Minimization of Q is generally
accomplished by using dilute solution and adding the
precipitating from hot solution or by adjusting the pH of
the precipitation medium.
Digestion of crystalline precipitates (without stirring) for
some time after formation frequently yields a purer, more
filterable product. The improvement in filterability results
from the dissolution and recrystallization.
20. 11/1/2018 Deokate U A 20
Purity of precipitate
• When the ppt is separated out from solution it is
always not preferably pure and may be
contaminated even after washing
• The amount of impurities depends on nature of
PPt and condition of pptn
• It may be due to
– Co-precipitation
– Post precipitation, Surface adsorption
– Mixed crystal formation
– Occlusion and Mechanical Entrapment
21. 11/1/2018 Deokate U A 21
Coprecipitation
Coprecipitation is the phenomenon in which
soluble compounds are removed from solution
during precipitate formation.
There are four types of coprecipitation:
i) surface adsorption, ii) mixed-crystal formation,
iii) occlusion, iv) mechanical entrapment
Surface adsorption and mixed crystal formation
are equilibrium processes, whereas occlusion
and mechanical entrapment arise from the
kinetics of crystal growth.
22. 11/1/2018 Deokate U A 22
Surface Adsorption
Adsorption is a common source of coprecipitation that is
likely to cause significant contamination of precipitates with
large specific surface areas, that is coagulated colloids.
Coagulation of a colloid does not significantly decrease the
amount of adsorption because the coagulated solid still
contains large internal surface areas that remain exposed
to the solvent. The coprecipitated contaminant on the
coagulated colloid consists of the lattice ion originally
adsorbed on the surface before coagulation and the
counter ion of opposite charge held in the film of solution
immediately adjacent to the particle. The net effect of
surface adsorption is therefore the carrying down of an
otherwise soluble compound as a surface contaminant.
23. 11/1/2018 Deokate U A 23
Minimizing Adsorbed Impurities on Colloids
The purity of many coagulated colloids is improved by
digestion. During this process, water is expelled from the
solid to give a denser mass that has a smaller specific
surface area for adsorption.
Washing a coagulate colloid with a solution containing a
volatile electrolyte may also be helpful because any
nonvolatile electrolyte added earlier to cause coagulation
is displace by the volatile species. Washing generally does
not remove much of the primarily adsorbed ions because
the attraction between these ions and the surface of the
solid is too strong. Exchange occurs, however between
existing counter ions and ions in the wash liquid.
24. 11/1/2018 Deokate U A 24
Reprecipitation
A drastic but effective way to minimize the effects
of adsorption is reprecipitation, or double
precipitation. Here, the filtered solid is redissolved
and reprecipitated. The first precipitate ordinarily
carries down only a fraction of the contaminant
present in the original solvent. Thus, the solution
containing the redissolved precipitate has a
significantly lower contaminant concentration
than the original, and even less adsorption occurs
during the second precipitation. Reprecipitation
adds substantially to the time required for an
analysis.
25. 11/1/2018 Deokate U A 25
Mixed-Crystal Formation
In mixed-crystal formation, one of the ions in the crystal
lattice of a solid is replaced by an ion of another element.
For this exchange to occur, it is necessary that the two
ions have the same charge and that their sizes differ by no
more than about 5%. Furthermore, the two salts must
belong to the same crystal class. For example, MgKPO4, in
MgNH4PO4, SrSO4 in BaSO4, and MnS in CdS.
The extent of mixed-crystal contamination increases as
increases. Mixed-crystal formation is
the ratio of contaminant to analyte concentration
troublesome
because little can be done about it. Separation of the
interfering ion may have to be carried out before the final
precipitation step. Alternatively, a different precipitating
reagent may be used.
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Occlusion and Mechanical Entrapment
When a crystal is growing rapidly during precipitate
formation, foreign ions in the counter-ion layer may become
trapped, or occluded, within the growing crystal.
Mechanical entrapment occurs when crystals lie close
together during growth. Here, several crystals grow together
and in so doing trap a portion of the solution in a tiny pocket.
Both occlusion and mechanical entrapment are at a minimum
when the rate of precipitate formation is low, that is, under
conditions of low supersaturation. Digestion is often
remarkably helpful in reducing these types of copreipitation.
The rapid solution and reprecipitation that goes on at the
elevated temperature of digestion opens up the pockets and
allows the impurities to escape into the solution.
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Precipitation from Homogeneous Solution
technique in which a precipitating agent
Precipitation from homogeneous solution is a
is
generated in a solution of the analyte by a slow
chemical reaction. Local reagent excesses do not
occur because the precipitating agent appears
gradually and homogeneously throughout the
solution and reacts immediately with the analyte.
As a result, the relative supersaturation is kept low
homogeneously formed precipitates,
during the entire precipitation. In general,
both
colloidal and crystalline, are better suited for
analysis than a solid formed by direct addition of a
precipitating reagent.
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Steps in a gravimetric analysis
1. Preparation of the solution
2. Precipitation
3. Digestion
4. Filtration
5. Washing
6. Drying or ignition
7. Weighing
8. Calculation
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1.Preparation of analyte solution
1st
• Gravimetric analysis usually involves precipitation of
analyte from solution.
step – Sampling; Representative of bulk
2nd step - prepare the analyte solution (Dissolution)
• May need :
– preliminary separation to separate potential interferences
before precipitating analyte
– adjustment of solution condition (pH/temp/vol/conc of test
substance) to maintain low solubility of precipitate & max
precipitate formation. Eg Calcium oxalate insoluble in basic
medium
– Most of the substances are readily solute in water and can
be used as such. Some required special treatment as
treatment with HCl, HNO3, Aquaregia or fusing with basic
flux
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2.Precipitation process :
• The precipitating reagent is added at a
concentration that favors the formation of a "good"
precipitate.
• This may require low concentration, extensive
heating (often described as "digestion"), or careful
control of the pH.
• A large excess of pptant should be avoided because
this increases chances of adsorption on ppt.
• Test for completeness of pptation
• No new ppt should be formed after addition of
drop of ppting agent.
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3.Digestion of the Precipitate
• Let precipitate stand in contact with mother
liquor (the solution from which it was
precipitated), usually at high temp
• This process is called digestion, or
Ostwaldripening. The small particles tend to
dissolve and precipitate on the surfaces of the
larger crystals
• Digestion make larger crystals, reduce surface
contamination, reduce crystals imperfection
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• Ppt is separated from mother liquor
• Choice depends on nature of ppt , cost of media
and heating temp required for drying.
• Filtration medium used are
– Filter papers
– Filter pulps
– Filter mats
– Crucible fitted with porous plate (Sintered glass filters)
– Crucible to be used at high temperature
4. Filtration
33. Filtration media
• Filter papers: eg ash less filter papers
– No 41 (Fast), 40 (Medium), 42(Slow)
– 541, 540, 542 Grater mechanical strength
• Filter pulps
• Filter mats (Gooch crucible)
• Sintered glass crucibles
– Types G1 (100-120 ), G2 (40-50 ), G3 (20-30 ),
G4 (5-10 )
– They are resistant to chemical and easy to clean
11/1/2018 Deokate U A 33
34. • Sintered glass crucibles are used
to filter the precipitates.
• The crucibles first cleaned
thoroughly and then subjected to
the same regimen of heating and
cooling as that required for the
precipitate.
• This process is repeated until
constant mass has been
achieved, that is, until
consecutive weighing differ by
0.3 mg or less.
11/1/2018 Deokate U A 34
35. 11/1/2018 Deokate U A 35
5. Washing
• Co precipitated impurities esp those on
surface, removed by washing the precipitate
• Wet precipitate with mother liquor and which
will also be remove by washing
• Need to add electrolyte to the wash liquid
bcoz some precipitate cannot be wash with
pure water, peptization occur.
• Eg HNO3 for AgCl precipitate
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6) Drying or ignition
• To remove solvent and wash electrolytes
• Done by heating at 110 to 120°C for 1 to 2 hrs.
• Converts hygroscopic compound to non-
hygroscopic compound
• May used high temp if precipitate must be
converted to a more suitable form before
weighing
• Eg MgNH4PO4 convert to pyrophosphate
Mg2P2O7 by heating at 900°C.
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7) Weighing
• After the precipitate is allowed to cool
(preferably in a desiccator to keep it from
absorbing moisture), it is weighed (in the
crucible).
• Properly calibrated analytical balance
• Good weighing technique
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Organic Precipitates
• Organic precipitating agents have the
advantages of giving precipitates with very
solubility in water and a favorable gravimetric
factor.
• Most of them are chelating agents that forms
slightly insoluble, uncharged chelates with the
metal ions.
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Gravimetric Analysis: Weight
Relationship
• in gravimetric method – the analyte (solute) is converted to
precipitate which is then weight
• From the weight of the precipitate formed in a gravimetric
analysis, we can calculate the weight of the analyte
• Gravimetric factor (GF) = weight of analyte per unit weight of
precipitate.
• Obtain from ratio of F Wt of the analyte per F Wt precipitate,
multiplied by moles of analyte per mole of precipitate
obtained from each mole of analyte
• GF = f wt analyte (g/mol) x a (mol analyte/mol precipitate)
• f wt precipitate (g/mol) b
• = g analyte / g precipitate
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Example 1 of gravimetric factor
• If Cl2 in a sample is converted to chloride and precipitated as AgCl, the
weight of Cl2 that gives
• 1g of AgCl is?
• F wt Cl = 35.453, F wt Ag = 107.868
• GF = f wt analyte (g/mol) x a (mol analyte/mol precipitate)
• f wt precipitate (g/mol) b
• = g analyte / g precipitate
• GF = f wt analyte (g/mol) x a (mol analyte/mol precipitate)
• f wt precipitate (g/mol) b
• = g analyte / g precipitate
• g Cl2 = g AgCl x f wt analyte (g/mol) x a
• f wt precipitate (g/mol) b
• = 1 AgCl x 70.906 g/mol x 1 mol
• 143.321 g/mol 2 mol
• = 0.2474 g
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EXAMPLE 2
• A 0.3516g sample of commercial phosphate
detergent was ignited at a red heat to destroy the
organic matter. The residue was then taken up in
hot HCl which converted P to H3PO4. The
phosphate was precipitated with Mg2+ followed
by aqueous NH3 to form MgNH4PO4.6H2O. After
being filtered and washed, the precipitate was
converted to Mg2P2O7 (FW=222.57) by ignition
at 100ºC. This residue weighed 0.2161g. Calculate
the percent P (FW = 30.974) in the sample.