This document provides information about chemistry experiments conducted by a class to determine melting points and boiling points of substances. It describes the procedure, materials, and observations for experiments to determine the melting point of a solid substance using a capillary tube and thermometer. It also outlines the similar process used to determine the boiling point of a liquid, involving heating a test tube of the liquid in a paraffin bath and noting the temperature when bubbles begin and stop escaping from a sealed capillary tube. The document also discusses purification of substances by crystallization and pH changes.
Heat transfer is the process of transferring heat from a high temperature object or system to a lower temperature one. It occurs due to a temperature difference and can happen through conduction, convection, or radiation. Heat transfer is important in many pharmaceutical processes like evaporation, distillation, drying, sterilization, and crystallization. Heat exchangers and heat interchangers are devices that facilitate heat transfer between fluids through conduction across a metal wall, allowing the transfer of heat from one liquid or gas to another. Tubular heat exchangers in particular provide a large surface area for heat transfer in a compact volume.
This document discusses different types of thermodynamic diagrams used to analyze thermodynamic processes and systems. It describes P-h, T-s, and H-T diagrams. A P-h diagram shows pressure vs enthalpy and can be used for any pure substance. It has liquid-vapor regions where two phases coexist. A T-s diagram, which is frequently used to analyze energy transfer systems, shows temperature vs entropy. It also has a liquid-vapor region where two phases coexist and the heat of a process equals the area under the T-s curve. Both P-h and T-s diagrams exhibit similar features and can be constructed for any pure substance.
Sublimation is the direct change of a solid substance into a gas without passing through the liquid state. Examples of substances that sublime include NH4Cl, I2, naphthalene, and benzoic acid. The pure solid obtained after sublimation is called the sublimate, while the original solid undergoing sublimation is the sublimand. Sublimation is carried out by slowly heating the sublimand over a sand bath under an inverted funnel that is cooled to cause the gaseous sublimate to condense on the inner side of the funnel. Sublimation is used to purify volatile thermally stable compounds and separate them from non-volatile substances.
Vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature. It relates to the evaporation rate of a liquid and is affected by factors like temperature, composition of mixtures, and presence of solids or liquids. Vapor pressure increases non-linearly with temperature and the boiling point of a liquid is reached when its vapor pressure equals atmospheric pressure. It plays an important role in cloud formation through processes like condensation, supersaturation, and Raoult's law governing vapor pressures in mixtures.
determination of melting point of liquid organic compoundyousifhawlery
Yousif Jameel, a student at Hawler Medical University's College of Pharmacy, prepared this document on determining the melting point of organic compounds. The document discusses the necessary equipment, safety considerations, factors that influence melting point such as molecular size and symmetry, and how variations in conditions can impact melting point. The purpose is to use melting point to determine purity, identify unknown compounds, and accurately obtain melting points using a Mel-Temp apparatus.
This document describes the precipitation method for determining the chloride ion concentration of a solution by titration with silver nitrate. Silver nitrate is added until all chloride ions are precipitated as silver chloride. Additional silver ions then react with potassium chromate indicator to form a red-brown silver chromate precipitate, signaling the endpoint. The method can be used to analyze water samples. It involves titrating aliquots of the sample with a standardized silver nitrate solution until concordant results are obtained.
Heat transfer is the process of transferring heat from a high temperature object or system to a lower temperature one. It occurs due to a temperature difference and can happen through conduction, convection, or radiation. Heat transfer is important in many pharmaceutical processes like evaporation, distillation, drying, sterilization, and crystallization. Heat exchangers and heat interchangers are devices that facilitate heat transfer between fluids through conduction across a metal wall, allowing the transfer of heat from one liquid or gas to another. Tubular heat exchangers in particular provide a large surface area for heat transfer in a compact volume.
This document discusses different types of thermodynamic diagrams used to analyze thermodynamic processes and systems. It describes P-h, T-s, and H-T diagrams. A P-h diagram shows pressure vs enthalpy and can be used for any pure substance. It has liquid-vapor regions where two phases coexist. A T-s diagram, which is frequently used to analyze energy transfer systems, shows temperature vs entropy. It also has a liquid-vapor region where two phases coexist and the heat of a process equals the area under the T-s curve. Both P-h and T-s diagrams exhibit similar features and can be constructed for any pure substance.
Sublimation is the direct change of a solid substance into a gas without passing through the liquid state. Examples of substances that sublime include NH4Cl, I2, naphthalene, and benzoic acid. The pure solid obtained after sublimation is called the sublimate, while the original solid undergoing sublimation is the sublimand. Sublimation is carried out by slowly heating the sublimand over a sand bath under an inverted funnel that is cooled to cause the gaseous sublimate to condense on the inner side of the funnel. Sublimation is used to purify volatile thermally stable compounds and separate them from non-volatile substances.
Vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature. It relates to the evaporation rate of a liquid and is affected by factors like temperature, composition of mixtures, and presence of solids or liquids. Vapor pressure increases non-linearly with temperature and the boiling point of a liquid is reached when its vapor pressure equals atmospheric pressure. It plays an important role in cloud formation through processes like condensation, supersaturation, and Raoult's law governing vapor pressures in mixtures.
determination of melting point of liquid organic compoundyousifhawlery
Yousif Jameel, a student at Hawler Medical University's College of Pharmacy, prepared this document on determining the melting point of organic compounds. The document discusses the necessary equipment, safety considerations, factors that influence melting point such as molecular size and symmetry, and how variations in conditions can impact melting point. The purpose is to use melting point to determine purity, identify unknown compounds, and accurately obtain melting points using a Mel-Temp apparatus.
This document describes the precipitation method for determining the chloride ion concentration of a solution by titration with silver nitrate. Silver nitrate is added until all chloride ions are precipitated as silver chloride. Additional silver ions then react with potassium chromate indicator to form a red-brown silver chromate precipitate, signaling the endpoint. The method can be used to analyze water samples. It involves titrating aliquots of the sample with a standardized silver nitrate solution until concordant results are obtained.
Heat exchangers transfer heat from one medium to another. They are classified by flow configuration and construction. Key flow configurations are parallel, counter, and cross flow. Main construction types are shell and tube, and plate heat exchangers. Heat transfer is calculated using methods like log mean temperature difference (LMTD) and number of transfer units (NTU). Standards like TEMA provide guidelines for shell and tube heat exchanger design and components.
This document discusses various distillation techniques used to separate liquid mixtures. It begins by defining distillation as a process that separates substances based on differences in their vapor pressures. It then describes several distillation methods including simple distillation, fractional distillation, steam distillation, and molecular distillation. For each method, it provides details on the operating principles, typical equipment setup, and common applications. The document serves to introduce various distillation unit operations and their uses in separating chemical substances.
Volhard's method is an indirect argentometric titration procedure used to determine anions that precipitate with silver ions. It involves adding excess silver nitrate to the analyte to form a silver salt precipitate. The unreacted silver ions are then back titrated with a standard thiocyanate solution using an iron(III) indicator to detect the endpoint color change from red to bright lemon yellow. Volhard's method is useful for determining halides and other anions like phosphate, arsenate, and chromate, especially in acidic conditions where carbonate and oxalate do not interfere.
1. The document describes a lab experiment to isolate limonene from orange peels through steam distillation. Peels are blended with water and distilled to obtain an "essential oil" containing limonene, which is then extracted and characterized using gas chromatography.
2. Key steps include grinding orange peels, distilling the peels to obtain limonene, extracting limonene using liquid-liquid extraction, and analyzing the isolated limonene using gas chromatography to determine its boiling point.
3. Steam distillation is used because it allows isolation of limonene at a lower temperature than normal distillation, preventing decomposition of the thermally sensitive terpene compounds like limonene.
This document summarizes various distillation techniques including differential distillation, flash vaporization, continuous rectification, and determining the ideal number of plates. It discusses mass balances, operating lines, reflux ratios, and how changing the number of plates and reflux ratio influences distillation column design and performance. Key aspects covered include equilibrium relationships, material flowing between plates, determining flow rates, and using diagrams to analyze fractionation.
Recrystallization is a technique used to purify compounds by dissolving an impure sample in a minimum amount of hot solvent, allowing the solution to cool slowly so that the desired compound crystallizes while impurities remain in solution, then collecting and washing the crystals. There must be a difference in solubility between the compound and impurities for effective separation. Organic compounds are typically more soluble in hot solvents than cold, allowing crystallization upon cooling.
The first 4 alkanes are gases, the next 13 are liquids, and higher alkanes after C18 are waxy solids. Alkanes are nonpolar and insoluble in water but soluble in nonpolar solvents. The boiling point of alkanes increases with molecular weight in a steady manner, while the melting point does not. Density also increases with larger alkane molecules. Branched chain alkanes have lower boiling points than their straight chain isomers.
This document provides guidance on mixing dry particulate solids. It discusses key differences between mixing solids versus liquids and gases. Namely, solids have no diffusion, particle properties can cause non-random movement, and particles are much larger than molecules. The document also covers qualitative and quantitative ways to assess mixture quality, such as scale of segregation and variance. It provides equations to calculate the theoretical best mixture quality based on formulation and scale of scrutiny. Selection of an appropriate mixer depends on whether the solids are free-flowing or cohesive. Sampling methods are important to properly assess mixture quality.
Distillation is a separation process that involves boiling a liquid mixture and condensing the vapor to obtain purified fractions. There are several types of distillation: simple distillation separates compounds based on differences in boiling points; fractional distillation is used for very similar compounds through repeated distillation in a fractionating column; steam distillation utilizes steam to distill compounds that have high boiling points; and distillation under reduced pressure allows heat-sensitive compounds to be distilled at lower temperatures. Distillation has many applications in areas like extracting essential oils, purifying organic compounds, and separating immiscible liquids.
Thermochemistry is the study of heat changes in chemical reactions and phase changes. There are two types of energy - kinetic energy, which is the energy of motion, and potential energy, which is stored energy like that in chemical bonds. Energy cannot be created or destroyed, only converted between kinetic and potential forms. Heat is a transfer of energy between objects due to a temperature difference, flowing from warmer to cooler until equal temperatures are reached. Exothermic reactions release heat while endothermic reactions absorb heat from their surroundings.
Sublimation is the direct change of a substance from the solid to the gas phase without passing through the liquid phase. It is an endothermic process that occurs below the triple point of a substance. During sublimation, heat provides energy for molecules to overcome attractive forces and escape as a gas. Sublimation is used to purify solids by heating them under reduced pressure so the pure substance condenses away from any non-volatile residues. It has applications in fields like pharmaceuticals, fingerprint detection, and producing special effects.
Water intake and treatment process at lilongwe water boardShareef Ngunguni
In Malawi,Lilongwe water Board is a major supply of water to different urban locations. Dirty water abstracted is converted into clean and portable water by physical,biological and chemical processes. Lilongwe water board disinfect the water by chlorination. Different tests are carried out every 3hrs to implement HACCP and ensure safe water to people.
Evaporation is the process by which a liquid is converted into vapor below the boiling point. There are four main factors that affect the rate of evaporation: temperature, humidity, wind speed, and surface area. Higher temperatures, lower humidity, stronger winds, and larger surface areas of liquid all increase the rate at which evaporation occurs.
Phenol and aniline are organic compounds derived from benzene. Phenol, also known as carbolic acid, contains a hydroxyl group bonded to an aromatic hydrocarbon. It can be prepared through oxidation of benzene, cumene, chlorobenzene, or diazonium salts. Phenol undergoes acylation, halogenation, carboxylation, and other reactions. Its structure exhibits resonance. Aniline contains an amino group bonded to a phenyl group. It can be prepared from nitrobenzene, chlorobenzene, or benzoic acid. Aniline undergoes various substitution and addition reactions. Its structure also exhibits resonance, contributing to its weak basicity.
The document discusses Hess's law, which states that the heat of reaction is the same whether a chemical process occurs in one or multiple steps. Specifically:
- Hess's law allows adding together multiple chemical equations to determine the enthalpy change of the overall equation.
- Two examples are provided to demonstrate calculating the enthalpy change of an overall reaction by combining individual reaction enthalpies.
- In both examples, the individual reactions are rearranged and combined to produce the overall reaction, and the enthalpy terms are summed to find the enthalpy change of the overall reaction.
The document discusses different types of heat treatment furnaces. It describes batch furnaces, which are manually loaded and unloaded, and continuous furnaces, which have an automatic conveying system. Some common batch furnaces include box, car, elevator, and bell furnaces. Pit furnaces heat long objects vertically. Salt bath furnaces submerge parts in molten salt for heating, while fluidized bed furnaces use gas-fluidized particulate for heating.
This document discusses common functional groups found in organic compounds. It defines functional groups as atoms or groups of atoms that confer similar chemical properties and reactivity. The document then lists and provides examples of common functional groups including alkanes, alkenes, alkynes, aromatics, haloalkanes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, and amides. It emphasizes that functional groups are important for classifying organic compounds, identifying sites of chemical reactions, and naming organic compounds.
This document provides information on distillation, including definitions, applications, terminology, and different types of distillation methods. It defines distillation as a process of separating components of a liquid mixture through vaporization and condensation. Some key applications mentioned include separation of volatile oils, purification of organic solvents and drugs, and refining of petroleum products. Various distillation assembly equipment and concepts such as the still, condenser, receiver, and Raoult's law are also described. Finally, different classifications of distillation methods like simple distillation, fractional distillation, and steam distillation are briefly outlined.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise boosts blood flow, releases endorphins, and promotes changes in the brain which help regulate emotions and stress levels.
This document provides instructions for an experiment to separate a mixture using various physical properties. The mixture contains naphthalene, salt, and sand. Naphthalene is separated through sublimation by heating the mixture and collecting the solid that forms on the evaporating dish. Salt is then dissolved in water. Filtration is used to separate the dissolved salt from the insoluble sand. Finally, the salt water solution is evaporated, leaving behind only the salt. The experiment demonstrates various separation techniques including sublimation, dissolution, filtration, and evaporation.
The document describes an experiment to separate and purify a mixture of liquids using fractional distillation. Key steps include: (1) setting up a distillation apparatus with a round bottom flask, fractionating column, condenser and receiver flask; (2) heating a 10mL mixture of rubbing alcohol which is distilled and results in a decreasing volume collected over time; (3) recording temperature and volume collected every 4 minutes until distillation is complete, showing separation of the mixture.
Heat exchangers transfer heat from one medium to another. They are classified by flow configuration and construction. Key flow configurations are parallel, counter, and cross flow. Main construction types are shell and tube, and plate heat exchangers. Heat transfer is calculated using methods like log mean temperature difference (LMTD) and number of transfer units (NTU). Standards like TEMA provide guidelines for shell and tube heat exchanger design and components.
This document discusses various distillation techniques used to separate liquid mixtures. It begins by defining distillation as a process that separates substances based on differences in their vapor pressures. It then describes several distillation methods including simple distillation, fractional distillation, steam distillation, and molecular distillation. For each method, it provides details on the operating principles, typical equipment setup, and common applications. The document serves to introduce various distillation unit operations and their uses in separating chemical substances.
Volhard's method is an indirect argentometric titration procedure used to determine anions that precipitate with silver ions. It involves adding excess silver nitrate to the analyte to form a silver salt precipitate. The unreacted silver ions are then back titrated with a standard thiocyanate solution using an iron(III) indicator to detect the endpoint color change from red to bright lemon yellow. Volhard's method is useful for determining halides and other anions like phosphate, arsenate, and chromate, especially in acidic conditions where carbonate and oxalate do not interfere.
1. The document describes a lab experiment to isolate limonene from orange peels through steam distillation. Peels are blended with water and distilled to obtain an "essential oil" containing limonene, which is then extracted and characterized using gas chromatography.
2. Key steps include grinding orange peels, distilling the peels to obtain limonene, extracting limonene using liquid-liquid extraction, and analyzing the isolated limonene using gas chromatography to determine its boiling point.
3. Steam distillation is used because it allows isolation of limonene at a lower temperature than normal distillation, preventing decomposition of the thermally sensitive terpene compounds like limonene.
This document summarizes various distillation techniques including differential distillation, flash vaporization, continuous rectification, and determining the ideal number of plates. It discusses mass balances, operating lines, reflux ratios, and how changing the number of plates and reflux ratio influences distillation column design and performance. Key aspects covered include equilibrium relationships, material flowing between plates, determining flow rates, and using diagrams to analyze fractionation.
Recrystallization is a technique used to purify compounds by dissolving an impure sample in a minimum amount of hot solvent, allowing the solution to cool slowly so that the desired compound crystallizes while impurities remain in solution, then collecting and washing the crystals. There must be a difference in solubility between the compound and impurities for effective separation. Organic compounds are typically more soluble in hot solvents than cold, allowing crystallization upon cooling.
The first 4 alkanes are gases, the next 13 are liquids, and higher alkanes after C18 are waxy solids. Alkanes are nonpolar and insoluble in water but soluble in nonpolar solvents. The boiling point of alkanes increases with molecular weight in a steady manner, while the melting point does not. Density also increases with larger alkane molecules. Branched chain alkanes have lower boiling points than their straight chain isomers.
This document provides guidance on mixing dry particulate solids. It discusses key differences between mixing solids versus liquids and gases. Namely, solids have no diffusion, particle properties can cause non-random movement, and particles are much larger than molecules. The document also covers qualitative and quantitative ways to assess mixture quality, such as scale of segregation and variance. It provides equations to calculate the theoretical best mixture quality based on formulation and scale of scrutiny. Selection of an appropriate mixer depends on whether the solids are free-flowing or cohesive. Sampling methods are important to properly assess mixture quality.
Distillation is a separation process that involves boiling a liquid mixture and condensing the vapor to obtain purified fractions. There are several types of distillation: simple distillation separates compounds based on differences in boiling points; fractional distillation is used for very similar compounds through repeated distillation in a fractionating column; steam distillation utilizes steam to distill compounds that have high boiling points; and distillation under reduced pressure allows heat-sensitive compounds to be distilled at lower temperatures. Distillation has many applications in areas like extracting essential oils, purifying organic compounds, and separating immiscible liquids.
Thermochemistry is the study of heat changes in chemical reactions and phase changes. There are two types of energy - kinetic energy, which is the energy of motion, and potential energy, which is stored energy like that in chemical bonds. Energy cannot be created or destroyed, only converted between kinetic and potential forms. Heat is a transfer of energy between objects due to a temperature difference, flowing from warmer to cooler until equal temperatures are reached. Exothermic reactions release heat while endothermic reactions absorb heat from their surroundings.
Sublimation is the direct change of a substance from the solid to the gas phase without passing through the liquid phase. It is an endothermic process that occurs below the triple point of a substance. During sublimation, heat provides energy for molecules to overcome attractive forces and escape as a gas. Sublimation is used to purify solids by heating them under reduced pressure so the pure substance condenses away from any non-volatile residues. It has applications in fields like pharmaceuticals, fingerprint detection, and producing special effects.
Water intake and treatment process at lilongwe water boardShareef Ngunguni
In Malawi,Lilongwe water Board is a major supply of water to different urban locations. Dirty water abstracted is converted into clean and portable water by physical,biological and chemical processes. Lilongwe water board disinfect the water by chlorination. Different tests are carried out every 3hrs to implement HACCP and ensure safe water to people.
Evaporation is the process by which a liquid is converted into vapor below the boiling point. There are four main factors that affect the rate of evaporation: temperature, humidity, wind speed, and surface area. Higher temperatures, lower humidity, stronger winds, and larger surface areas of liquid all increase the rate at which evaporation occurs.
Phenol and aniline are organic compounds derived from benzene. Phenol, also known as carbolic acid, contains a hydroxyl group bonded to an aromatic hydrocarbon. It can be prepared through oxidation of benzene, cumene, chlorobenzene, or diazonium salts. Phenol undergoes acylation, halogenation, carboxylation, and other reactions. Its structure exhibits resonance. Aniline contains an amino group bonded to a phenyl group. It can be prepared from nitrobenzene, chlorobenzene, or benzoic acid. Aniline undergoes various substitution and addition reactions. Its structure also exhibits resonance, contributing to its weak basicity.
The document discusses Hess's law, which states that the heat of reaction is the same whether a chemical process occurs in one or multiple steps. Specifically:
- Hess's law allows adding together multiple chemical equations to determine the enthalpy change of the overall equation.
- Two examples are provided to demonstrate calculating the enthalpy change of an overall reaction by combining individual reaction enthalpies.
- In both examples, the individual reactions are rearranged and combined to produce the overall reaction, and the enthalpy terms are summed to find the enthalpy change of the overall reaction.
The document discusses different types of heat treatment furnaces. It describes batch furnaces, which are manually loaded and unloaded, and continuous furnaces, which have an automatic conveying system. Some common batch furnaces include box, car, elevator, and bell furnaces. Pit furnaces heat long objects vertically. Salt bath furnaces submerge parts in molten salt for heating, while fluidized bed furnaces use gas-fluidized particulate for heating.
This document discusses common functional groups found in organic compounds. It defines functional groups as atoms or groups of atoms that confer similar chemical properties and reactivity. The document then lists and provides examples of common functional groups including alkanes, alkenes, alkynes, aromatics, haloalkanes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, and amides. It emphasizes that functional groups are important for classifying organic compounds, identifying sites of chemical reactions, and naming organic compounds.
This document provides information on distillation, including definitions, applications, terminology, and different types of distillation methods. It defines distillation as a process of separating components of a liquid mixture through vaporization and condensation. Some key applications mentioned include separation of volatile oils, purification of organic solvents and drugs, and refining of petroleum products. Various distillation assembly equipment and concepts such as the still, condenser, receiver, and Raoult's law are also described. Finally, different classifications of distillation methods like simple distillation, fractional distillation, and steam distillation are briefly outlined.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise boosts blood flow, releases endorphins, and promotes changes in the brain which help regulate emotions and stress levels.
This document provides instructions for an experiment to separate a mixture using various physical properties. The mixture contains naphthalene, salt, and sand. Naphthalene is separated through sublimation by heating the mixture and collecting the solid that forms on the evaporating dish. Salt is then dissolved in water. Filtration is used to separate the dissolved salt from the insoluble sand. Finally, the salt water solution is evaporated, leaving behind only the salt. The experiment demonstrates various separation techniques including sublimation, dissolution, filtration, and evaporation.
The document describes an experiment to separate and purify a mixture of liquids using fractional distillation. Key steps include: (1) setting up a distillation apparatus with a round bottom flask, fractionating column, condenser and receiver flask; (2) heating a 10mL mixture of rubbing alcohol which is distilled and results in a decreasing volume collected over time; (3) recording temperature and volume collected every 4 minutes until distillation is complete, showing separation of the mixture.
This document discusses various techniques for purifying substances, including filtration, crystallization, distillation, and chromatography. It provides examples of how each technique works and the types of mixtures it can be used to separate. Key points include:
- Filtration separates insoluble solids from liquids by passing the mixture through a filter paper.
- Crystallization forms pure crystals of a soluble solid by slowly evaporating the solvent from a saturated solution.
- Distillation boils a liquid mixture and condenses the vapor to separate components with different boiling points.
- Chromatography separates mixtures by exploiting differences in how substances partition between a stationary and mobile phase.
(Science) Laboratory Operations and Techniquesjustinesolano
The document provides instructions for proper laboratory techniques including transferring solids and liquids, heating substances, separating solids from liquids through filtration and decantation, making saturated solutions, and determining odors. Students are to demonstrate these techniques precisely to avoid accidents and work efficiently in the lab. Key steps include using paper to transfer solids to test tubes without contamination, employing funnels or rods for precise liquid transfers, heating at angles without looking into tubes, allowing solids to settle before decanting or filtering mixtures, and cautiously sniffing odors from a distance.
This document discusses various techniques for purifying substances, including filtration, crystallization, distillation, and chromatography. It provides examples of how each technique works and the types of mixtures it can be used to separate. Key points include:
- Filtration separates insoluble solids from liquids by passing the mixture through a filter paper.
- Crystallization forms pure crystals of a soluble solid by slowly evaporating the solvent from a saturated solution.
- Distillation boils a liquid mixture and condenses the vapor to separate components with different boiling points.
- Chromatography separates mixtures by exploiting differences in how substances partition between a stationary and mobile phase.
This document summarizes a chemistry laboratory experiment on simple distillation. The experiment aims to separate a mixture of two miscible liquids with a boiling point difference of at least 25°C. The procedure involves heating the liquid mixture in a round-bottom flask attached to a condenser. Vapors form and travel up the condenser where they cool and drip into a collection flask. The temperature is recorded at each stage of distillation. The results show the primary boiling point, final boiling point, amounts distilled and remaining, and percentage of distilled material.
This document describes an experiment involving simple distillation and steam distillation. The objectives were to assemble and operate simple and steam distillation setups to purify samples. Simple distillation of toluene yielded a boiling point range of 100-110°C and 32.31% recovery. Steam distillation of p-dichlorobenzene yielded an 89% recovery and purification was confirmed with melting point tests. Distillation techniques were discussed including the use of glass beads to prevent bumping and the advantages of each distillation method for different substance types. The objectives of assembling and operating the distillation setups and purifying samples using both techniques were achieved.
CHEM 1411 Alternate Separation of a Mixture LabObjectives1. To unJinElias52
CHEM 1411 Alternate Separation of a Mixture LabObjectives:
1. To understand different physical separation techniques
2. To separate the components of a mixture of sand (SiO2), table salt (NaCl) and ammonium chloride (NH4Cl), using various separation techniques
3. To determine the percent composition of each component
4. To determine the percent recovery of the total mixtureMaterials:
· 2 g unknown sample
· Small evaporating dish
· Large evaporating dish
· Watch glass
· Bunsen burner
· Balance
· Clay triangle
· Clay square
· Glass stirring rod
· Evaporating dish tongsIntroduction:
Matter can be generally classified either by state (liquid, gas, or solid) or by composition. In terms of composition, there are two types of matter: pure substances and mixtures. A
pure substance is matter that has a fixed composition and distinct properties. Elements or compounds are pure substances (e.g. water, helium.) On the other hand, a
mixture is matter that consists of two or more pure substances physically combined in varying amounts (e.g. salt water). There are two types of mixtures: homogeneous and heterogeneous mixtures. Whereas a
homogeneous mixture is uniform throughout, the components of a
heterogeneous mixture vary throughout and can be distinguished. For instance, granite (a type of rock) is a heterogeneous mixture.
Regardless of the type of mixture, the components of a mixture can always be separated by physical means. Some examples of physical methods of separation are defined below.
Decantation is the rough separation of a liquid from a solid. It consists of pouring the liquid out and leaving the solid in the container.
No filter paper is needed in this process.
As an example,
sand and water can be separated by decantation.
Filtration is the fine separation of a solid material from a liquid with the help of filter paper and a funnel or other porous membrane. In this process, the solid or residue is collected on a filter paper. The liquid that passes through the filter paper is called the filtrate.
Extraction involves using a solvent to dissolve only one component of a mixture so that it can be removed from the other component(s). For example, if only one solid is soluble in water, extraction could be used to dissolve that component and then the aqueous solution can be removed from the mixture by decantation or filtration.
Distillation is a separation technique that uses the different boiling points of liquids. It consists of vaporizing a liquid substance out of a mixture of two or more liquids and condensing it into a separate container using a condenser. For example, alcohol can be separated from water in an aqueous solution by distillation because the alcohol has a lower boiling point than water.
Sublimation is the direct phase change from solid to gas. Ammonium chloride sublimates when heated. Thi ...
This document provides summaries of several common laboratory techniques and procedures:
1. It describes how to properly measure volume using graduated cylinders and pipettes, and how to read meniscus levels.
2. It explains how to weigh samples using balances, including zeroing the balance and using tare functions.
3. Common separation techniques like decantation, filtration, centrifugation, distillation, and chromatography are summarized.
- Distillation is a process that separates mixtures based on differences in boiling points. It involves heating a liquid mixture to form vapors, condensing the vapors back to liquid, and collecting the purified liquid fractions.
- There are several types of distillation including simple, steam, fractional, and vacuum distillation which vary based on conditions and mixtures separated.
- A laboratory experiment demonstrates simple distillation to separate ethanol and water using common distillation equipment like a round bottom flask, condenser, and receiver flask. The mixture is heated to form vapors that condense and drip into the collection flask.
1. Digital balances allow for precise mass measurements and are important for experiments requiring exact amounts of substances. They must be placed on a stable, flat surface and containers must be tared to remove their mass from calculations.
2. Beakers and Erlenmeyer flasks are used to hold liquids and solids. Beakers have a pour spout and are used for mixing and transferring chemicals. Flasks can hold reactions or liquid samples and catch filtrates.
3. Burettes held in clamps and stands allow for accurate liquid measurements and dispensing. They are filled and used with a beaker or flask underneath to deliver specific volumes of reagents.
Fractional distillation is used to separate complex hydrocarbon mixtures like crude oil into fractions with similar boiling points. Vapors rise in a fractional distillation column and condense, becoming progressively more concentrated. Each tray contains liquid in equilibrium that vaporizes the lighter hydrocarbons, leaving heavier liquid below. Common fractions include methane, ethane, LPG, gasoline, kerosene, diesel and asphalt. Repeated fractional distillation results in fairly pure distillates used for fuel, waxes and industrial feedstocks.
Rinse out the 250 mL flasks that you used to dilute the concentrated acid and base solutions. Weigh out 0.7 to 0.9 g of KHP (pictured below) into a 250 mL flask and dissolve it in 50 mL of distilled water. Add three drops of the phenolphthalein indicator in the flask (see below). Then place the flask under the base buret and start the titration
RELATIVE RATES OF COMPETING REACTIONS
Chemical behavior is a matter of relative rates of competing reactions.
The competing reaction which occurs the fastest, predominates (makes more product than the other competing reactions).
The predominate reaction is usually the reaction which was the easiest mechanism
STRUCTURE: The Functional Group
The atom or group of atoms that defines the structure of a particular family of organic compounds and, at the same time, determines their properties is called the functional
The document describes two methods for forming copper oxide. The first method heats copper powder, allowing it to react with oxygen in the air to form copper oxide. Comparing the masses of copper and copper oxide determines the empirical formula. The second method uses copper(II) sulfate solution reacted with sodium hydroxide to form a copper hydroxide precipitate. Heating this decomposes it into copper oxide and water vapor, allowing calculation of the empirical formula from the known quantities. Procedures are provided for both experiments.
The document outlines several ASTM standards for testing bituminous paving mixtures, including procedures for determining theoretical maximum specific gravity, extracting bitumen content, preparing specimens using a Marshall apparatus, measuring bulk specific gravity, and testing Marshall stability and flow. Key steps are described such as vacuum sealing samples to determine specific gravity, centrifugally extracting bitumen in solvent, compacting specimens to a given number of blows, submerging specimens to determine bulk specific gravity, and loading specimens in a Marshall apparatus to measure stability and flow.
Distillation is a process of separating mixtures by boiling and condensing their components with differing volatilities. It works by heating a liquid mixture to its boiling point, vaporizing components, and then condensing the vapor to liquid, allowing different components to separate. There are several types of distillation including simple distillation, fractional distillation, steam distillation, and vacuum distillation. Distillation is used in pharmacy to purify water and organic solvents, and prepare volatile oils, aromatic waters, and other official compounds.
This document discusses various distillation techniques including:
- Simple distillation where a liquid is boiled and the vapors are condensed.
- Fractional distillation which uses a fractionating column to separate mixtures based on differences in boiling points.
- Distillation under reduced pressure which lowers the boiling point by reducing external pressure, allowing distillation at lower temperatures.
- Steam distillation which uses steam to carry volatile compounds from a non-aqueous liquid into a condenser for collection.
- Molecular distillation techniques like centrifugal and wiped film stills which evaporate liquids in thin films under vacuum for high purity distillation.
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Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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2. Determination of Melting point
The melting point of a substance may be defined as the temperature at which the
substance changes from the solid state to the liquid state. It is a very useful
physical constant because a pure substance melts at a definite temperature and
has a sharp melting point while an impure substance has a lower melting point and
melts over a wide range. Therefore, determination of melting point is a very
convenient method to check the purity of a solid substance. Moreover, melting point
determination can be used to identify a substance by comparing its melting point with
the melting points of known substances.
Experiment
To determine the melting point of the given solid substance.
Requirements
100 ml beaker, thermometer, iron stand, clamp, tripod stand, stirrer, thin-walled
capillary tube 8 to 10 cm long and 1 to 2 mm diameter, spatula. Liquid paraffin.
Procedure
1. Powder the crystalline substance. Take a capillary tube and seal its one end by
heating (Fig. 3.1). For filling the substance make a heap of the powdered substance
on the porous plate. Push the open end of the capillary tube into the heap. Some
substance will enter into it. Now tap the sealed end of the capillary tube on the
porous plate gently. Fill the capillary tube up to 2-3 mm.
2. Attach the capillary tube to a thermometer which is immersed in a bath of liquid
paraffin. The surface tension of the bath liquid is sufficient to hold the capillary tube
3. in position.
3. Heat the beaker slowly and go on stirring the liquid in the beaker so that the
temperature remains uniform throughout. For this, a glass loop stirrer is moved up
and down. When the temperature is within 15° of the melting points of the pure
substance, the flame is lowered. Now, the temperature is allowed to rise slowly.
4. The temperature is noted when the substance starts melting. The temperature is
noted again when it is completely melted. The average of the two readings gives the
melting point of the substance.
Precautions
1. Use dry and powdered sample for the determination of melting point.
2. Keep the lower end of the capillary tube and the thermometer at the same level.
3. Packing of the powder should be uniform without any big air gaps in between the
solid particles.
4. Heating should be gradual and the bath should be stirred regularly to maintain
uniform temperature.
5. The bulb of the thermometer and the capillary sticking to it should not touch the
side or the bottom of the beaker.
6. Do not use rubber band for attaching the capillary tube to the thermometer.
Observations
Temperature at which the unknown substance begins to melt = t1°C
Temperature at which the substance completely melts = t2°C
Melting point of the unknown substance = (t1+t2)/2 °C
6. Determination of Boiling point
The boiling point of a liquid may be defined as the temperature at which the
vapour pressure of the liquid is equal to the atmospheric pressure exerted
upon the liquid surface.
The boiling point of the liquid depends upon the pressure exerted upon the liquid
surface. Since atmospheric pressure is different at different place, therefore a liquid
has different boiling points at different places. For the sake of comparison, we use
normal boiling points. The normal boiling point of a liquid may be defined as the
temperature at which vapour pressure of the liquid is equal to one standard
atmospheric pressure (760 mm).
The boiling point of a liquid increases if non-volatile impurities are present in it.
Experiment
To determine the Boiling point of the given solid substance.
Requirements
100 ml coming glass beaker, a small thin walled test tube, thermometer, a capillary
tube, a tripod stand, wire gauze, stirrer, iron stand with clamp, liquid paraffin or cone,
sulphuric acid and the given liquid.
Procedure
1. Take a small test tube and fill it two-third with the given liquid whose boiling point
is to be determined. Fix this tube to the thermometer with a rubber band. The rubber
band should be fixed near the mouth of the tube so that it remains outside the liquid
paraffin bath. Adjust the tube so that the bottom of the tube is somewhere at the
middle of the thermometer bulb.
2. Clamp the thermometer carrying test tube in an iron stand through a cork. Lower
the thermometer along with the tube into a liquid paraffin bath. Adjust the
thermometer so that its bulb is well under the acid and open end of the tube with the
rubber band is sufficiently outside the acid bath. .
3. Take a capillary tube 5-6 cm in length and seal it at about one cm from one end by
heating it in flame and giving a slight twist. Place this capillary in the test tube so that
sealed part of it stands in the liquid.
4. Start heating the liquid paraffin bath slowly and stir the bath gently. Keep an eye
on the liquid and the test tube and also on the thread of the mercury in the
thermometer. At first a bubble or two will be seen escaping at the end of the capillary
dipping in the liquid, but soon a rapid and continuous stream of air bubbles escapes
from it. This is the stage when the vapour pressure of the liquid in the sealed
capillary just exceeds the atmospheric pressure. Note the temperature when
continuous stream of bubbles starts coming out. Remove the flame and note the
7. temperature when the evolution of bubbles from the end of, the capillary tube just
stops. The mean of these two temperatures gives the boiling point of the liquid.
5. Allow the temperature fall by 10°C and repeat the heating and again note the
boiling point.
Precautions
1. Keep the lower end of the ignition tube and the thermometer bulb at the same
level.
2. Record the temperature as the boiling point at which brisk and continuous
evolution of the bubbles starts from the lower end of the capillary dipped in the liquid
organic compound.
3. If on placing the sealed capillary tube in the test tube, the liquid is seen rising in
the capillary tube, it indicates that the capillary tube is not properly sealed. Reject
this capillary tube and use a sealed new one.
4. The sealed point of the capillary tube should be well within the liquid.
5. The paraffin bath must be heated very slowly and the paraffin stirred to ensure
uniform heating.
8. Note. Paraffin can be safely heated up to 220°C while conc. H2SO4 can be heated up
to 280°C.For finding the melting points of solids, having lower melting points, liquid
paraffin may be used while for solids having melting points greater than 200°C
conc. H2SO4 may be used.
Observations
Boiling point
(I) t1°C
(ii) t2°C
Mean = t1°+t2°/2 = t° C
Table: Melting Points of Some Organic Compounds
9.
10. Purification of Chemical Substances by
Crystallisation
For chemical purposes the substances should be pure, completely free from any
type of impurity. Impurities may be soluble or insoluble in the solvent in which the
substance under consideration dissolves. So, method of purification of the substance
depends on the nature of the impurity present and there are large number of
methods available for the purification of the substance such as filtration,
sedimentation, decantation and crystallisation. The simple laboratory technique
applied for the purification of the substances by crystallisation is described below.
Process of Crystallisation
The process of crystallisation involves following steps:
1. Preparation of Solution of the Impure Sample
1. Take a clean beaker (250 ml) and add powdered impure sample under
consideration in it (~ 6.0 gm).
2. Add distilled water (25-30 ml) and stir contents gently with the help of glass rod
giving circular motion as shown in Fig. 5.1.
3. The solution in the beaker is heated (60°-70°C) on a wire gauze (Fig. 5.2).
4. Stir the solution continuously and add more of impure substance till no more of it
dissolves.
11. 2. Filtration of Hot Solution
1. Take a circular filter paper. First fold it one-half, then fold it one-fourth as shown in
Fig. 5.3. Open the filter paper, three folds on one side and one-fold on the other side
to get a cone (Fig. 5.3).
2. Take a funnel and fit the filter paper cone into the funnel so that the upper half of
the cone fits well into the funnel but lower part remains slightly away from the funnel.
12. 3. Wet the filter paper cone with a spray of water from a wash bottle pressing the
upper part of the filter paper cone gently against the wall of the funnel with the thumb
(Fig. 5.4).
4. Place the funnel on a funnel stand and place a clean china dish below the funnel
for the collection of the filtrate. To avoid splashing of the filtrate, adjust the funnel so
that its stem touches the wall of the dish.
5. Hold a glass rod in slanting position in your hand or with a precaution that the
lower end of the rod should reach into the filter paper cone but it does not touch it.
Pour the solution along the glass rod as shown in Fig. 5.5. The filtrate passes
through the filter paper and is collected into the china dish placed below. The
insoluble impurities are left behind on the filter paper.
13. 3. Concentration of Filtrate
1. Place the dish containing the clear filtrate over wire gauze, kept over a tripod
stand and heat it gently (Do not boil). Stir the solution with a glass rod (Fig. 5.6). This
is done to ensure uniform evaporation and to prevent formation of solid crust.
14. 2. When the volume of the solution is reduced to one-half, take out a drop of the
concentrated solution on one end of glass rod and cool it by blowing air (Fig. 5.7).
Formation of thin crust indicates that crystallisation point has reached.
3. Stop heating by removing the burner.
15. 4. Cooling the Concentrated Solution
1. Pour the concentrated solution into a crystallising dish. (It is a thin walled shallow
glass dish with a flat bottom and vertical sides. It has a spout to pour off the mother
liquor).
2. Cover the dish with a watch glass and keep it undisturbed.
3. As the solution cools, crystals separate out. The concentrated solution is cooled
slowly for better yield of the crystals.
Sometimes the china dish containing the concentrated solution is cooled by placing
on a beaker filled to the brim with cold water Fig. 5.8. Cooling may also be done by
keeping the china dish in open air depending upon the weather conditions.
5. Separation and Drying of Crystals
1. Decant off the mother liquor Fig. 5.9, and wash the crystals with cold water or
alcohol.
2. Dry the crystals by pressing them gently between the sheets of filter paper Fig.
5.10. The crystals can be dried by spreading them on a porous plate for some time
or by placing the crystals in vacuum desiccator.
Crystals have definite geometry and a definite shape. Fig. 5.11 shows some of these
shapes. Copper sulphate crystals are formed in triclinic shape, potash alum comes
out in octahedral geometry. Potassium nitrate crystals are needle like and ferrous
sulphate have monoclinic shape.
16.
17.
18. Experiments Based On pH Change
pH SCALE
In order to express the hydronium ion (H3O+
) concentration in a solution P.L.
Sorensen (1909) devised a logarithmic scale. This scale is known as pH scale.
The pH of a solution is defined as the negative logarithm of hydronium ion
concentration in moles per litre.
pH=−log[H3O+]
= log1H3O+
Acidity, Alkalinity, Neutrality of Solutions
neutral solution: H+ = OH− = 10−7M; pH = – 7
acidic solution: H+ > OH−, H+ > 10−7M, pH < 7.
basic solution: OH− > H+, H+ < 10−7M, pH > 7. (also called an alkaline solution)
Strong and Weak Acids and Bases
strong acid—an acid that is a strong electrolyte and has a pH < 3.
For example, H2SO4, HCl, HBr, HI, HNO3
weak acid—an acid that is a weak electrolyte or an ionic compound that partially
reacts with water to form hydrogen ions in aqueous solution. It will have a pH greater
than 3 but less than 7.
For example, H2S, H3PO4, CH3COOH, H2CO3.
strong base—a hydroxide that is a strong electrolyte and has a pH >11.
For example, NaOH, KOH, Ba (OH)2.
weak base—a hydroxide that is a weak electrolyte or a compound that partially
reacts with water to form hydroxide ions in aqueous solution. Its pH will be less than
11 but greater than 7.
For example, carbonates, bicarbonates, ammonia (ammonium hydroxide),
phosphates.
salt—an ionic compound produced by reacting an acid and a base. It will have a pH
close to 7.
Ionic Product of Water
Pure water is very weakly ionised. So, there is an equilibrium between ionised and
unionised molecules.
19. In general, it has been observed that at room temperature all neutral solutions have
pH equal to 7, all acidic solutions have pH less than 7 and all basic solutions have
pH more than 7.
Common Ion Effect
Common ion effect may be defined as the suppression of degree of dissociation of a
weak electrolyte by the addition of a small amount of some strong electrolyte having
a common ion with that of the weak electrolyte.
Consider for example, NH4OH which is a weak electrolyte and there is an
equilibrium between unionised molecules and its ions.
When NH4Cl, a strong electrolyte, is added to it, NH4Cl ionises as
Due to the presence of common NH+4 ions the equilibrium (6.1) shifts in the
backward direction and degree of dissociation of NH4OH is supressed. So the
concentration of OH− ions decreases and hence concentration of H3O+ ions
increases. Thus, pH of the solution is lowered.
Similarly consider acetic acid, a weak electrolyte
When sodium acetate, a strong electrolyte is added to it, CHgCOONa ionises as :
20. Due to the presence of common CH3COO− ions the equilibrium (6.2) shifts in the
backward direction and so concentration of H3O+ ions decrease and hence that of
OH- ions increases. Therefore, pH of solution increases.
Salts when dissolved in water may undergo hydrolysis producing acidic or basic
solutions. Hydrolysis of salts may be defined as the interaction of ions of the salt
with water producing acidic or basic solution.
21. Serial
No.
Indicator pH range
Colour in
acidic
medium
Colour in alkaline medium
1. Thymol blue 1.2-2.8 Red Yellow
2. Methyl yellow 2.9-4.0 Red Yellow
3.
Bromophenol
blue
3.0-4.6 Yellow Blue
4. Congo red 3.0-5.0 Violet Red
5. Methyl orange 3.1-4.4 Red Yellow
6. Methyl red 4.2-6.3 Red Yellow
7. Phenol red 6.8-8.4 Yellow Red
23. Hydrolysis of salts of strong bases and weak acids produces alkaline solution on
hydrolysis. For example, the aqueous solution of sodium acetate is alkaline due to
the presence of excess hydroxyl ions in the solution.
Hydrolysis of salts of strong acids and weak bases produces acidic solution due to
the presence of excess hydronium ions in the solution. For example, an aqueous
solution of ammonium chloride is acidic in nature.
Hydrolysis of salts of weak acids and weak bases gives almost neutral solutions. For
example,
Salts of strong acids and strong bases do not undergo hydrolysis and hence
their aqueous solutions are neutral.
Table 6.1. Colour Changes and pH range of Certain Indicators
Universal Indicator
A universal indicator is prepared by mixing a number of common indicators together
so that the mixture obtained can pass through a series of colour changes over a
much wider pH range. For example, one such mixture which may show various
colours at different pH is as given in Table 6.2.
Table 6.2. Colours of Universal Indicator at Different pH Values
pH Colour
24. 3.0 Red
5.0 Orange red
5.5 Orange
6.0
Orange-
yellow
7.0-7.5
Greenish-
yellow
8.0 Green
9.5 Blue
10.0 Violet
Such mixtures are commonly known as universal indicators. Universal indicators are
available commercially as solutions and as test papers. A pH paper is a strip of
paper which is prepared by dipping the strip in the solutions of different indicators
and then drying them.
pH paper can be used to find the approximate pH of any solution. The pH paper is
dipped in a given sample of the solution, the colour developed in the paper is
compared with the colour chart and approximate pH of the solution can be predicted.
A pH paper is shown in Fig. 6.1.