CHE 211 Study Guide - Midterm Guide: Lead, Boiling Point, Distillation

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Organic Chemistry 2 – Chemical Purification & Separation

Distillation Theory

▪ The purity of the distillate will increase with the increase in the number of

vaporization/condensation cycles --> this is the number of times a liquid is vaporized

and condensed on its way to the receiving flask

▪ The greater number of cycles means the more pure the distilland will be

▪ Simple distillation has one vaporization-condensation cycle; simple distillation works

best only for the purification of a liquid that contains either non-volatile impurities or

small amounts of higher or lower boiling impurities

▪ Fractional distillation has several vaporization-condensation cycles; fractional

distillation goes through many vaporization/condensation cycles --> it is usually

employed to separate the components of mixture or to purify a liquid that contains

large amounts of volatile impurities

▪ Coside a itue of two ideal liuids that obe both Raoult’s Law ad Dalto’s Law

▪ Ideal liquids that have ideal vapors that obey both Raoult's law and Dalton's law

 Raoult’s Law: PA = XA · P°A

 Raoult's Law = It states that the partial vapor pressure of each component

of an ideal mixture of liquids is equal to the vapor pressure of the pure

component multiplied by its mole fraction in the mixture.

 Mole fraction (XA) = moles A/(moles A + moles B)

• Raoult's Law states that at a given temperature and pressure, the partial

pressure (Pa) of a compound in an ideal solution is equal to the vapor

pressure of the pure compound (P*a) multiplied by its mole fraction (Xa)

• The mole fraction is a measure of concentration --> it is the number of

moles of one particular compound in a mixture divided by the total

number of moles in the mixture

 Dalton’s Law: PTotal = PA + PB

฀ Dalton's Law of Partial pressures states that the total pressure of a mixture

of gases is the sum of the partial pressure of its individual components

฀ Example: For a mixture of compound A and B --> they both boil when the

sum of the partial pressures (Pa + Pb) equals atmospheric pressure

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Document Summary

Organic chemistry 2 chemical purification & separation. Ideal liquids that have ideal vapors that obey both raoult"s law and dalton"s law. Raoult"s law: pa = xa p a. Raoult"s law = it states that the partial vapor pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture. Dalton"s law: ptotal = pa + pb. Dalton"s law of partial pressures states that the total pressure of a mixture of gases is the sum of the partial pressure of its individual components. Example: for a mixture of compound a and b --> they both boil when the sum of the partial pressures (pa + pb) equals atmospheric pressure. The liquid compound that has the higher vapour pressure. Lets assume we have a mixture of 50% compound a and.

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Introduction:

This week you will be learning another important technique in the organic chemistry laboratory â distillation. Distillation uses the difference in boiling point of two miscible liquids and thus separates compounds by exploiting different volatilities. While often used in the chemical laboratory, the process itself is a physical separation that uses phase changes (gas / liquid) to effect either complete or partial separation. In the simplest form distillation consists of 2 phase changes, evaporation followed by one condensation step (simple distillation), whereas fractional distillation repeats the process of evaporation followed by condensation inside a distillation column. Besides the physical separation, distillation also provides you with a measure of purity as you will be able to constantly monitor the boiling point of the distillate and compare it to literature values. To corroborate your results of this weekâs experiment, you will additionally perform gas chromatography of the distillates that you obtain. Gas chromatography allows for the analytical separation of compounds based on their boiling point and will serve in your experiment as a basis for determining the purity of the distillate. You will be given a mixture of 2 alcohols and will perform either a simple or a fractional distillation on it. You will then analyze your distillates using gas chromatography, determine the percent composition and thus the success of your distillation.

Questions for the experiment and the analysis:

1) Using the provided GC sample runs including integrations of each of the alcohol mixtures BEFORE the distillation, determine the percent of each of the alcohols in the sample

2) Obtain and tabulate the results of the other five procedures carried by the class

3) For all six procedures, compare the boiling ranges throughout the distillation, as well as the percent composition of the first and last collected fraction

4) Using this data, determine which distillations were successful in separating the two alcohols and which ones were unsuccessful. Make sure to compare this with the theory of distillation and the performance you should expect for simple vs fractional distillation

5) Based on those results, what factor seemingly determines whether a good separation is possible through distillation?

Lab Results:

Impure Methanol:Propanol

Peak 1: Retention Time (min)= 1.290, Area= 19.56, %Area= 7.25

Peak 2: Retention Time (min)= 2.140, Area= 250.19, %Area=92.75

Impure Methanol:Ethanol

Peak 1: Retention Time (min)= 1.265, Area= -4.83, %Area= 14.00

Peak 2: Retention Time (min)= 1.405, Area= -29.67, %Area= 86.00

Impure Methanol:Butanol

Peak 1: Retention Time (min)= 1.305, Area= 30.79, %Area= 3.41

Peak 2: Retention Time (min)= 3.690, Area= 872.07, %Area= 96.59

5 Procedures Carried by the Class Results:

Student 1:

Methanol:Ethanol- first test tube (simple distillation)

Peak 1: Retention Time (min)= 0.860, Area= 0.89, %Area= 4.42

Peak 2: Retention Time (min)= 1.035, Area= 16.92, %Area= 84.16

Peak 3: Retention Time (min)= 1.110, Area= 2.29, %Area= 11.41

Methanol:Ethanol- last test tube (simple distillation)

Peak 1: Retention Time (min)= 1.195, Area= 198.76, %Area= 100.00

Student 2:

Methanol:Ethanol- first test tube (simple distillation)

Peak 1: Retention Time (min)= 1.755, Area= 12.87, %Area= 100.00

Methanol:Ethanol- last test tube (simple distillation)

Peak 1: Retention Time (min)= 1.615, Area= 44.11, %Area= 100.00

Student 3:

Methanol:Ethanol- first test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.555, Area= 11.11, %Area= 98.84

Peak 2: Retention Time (min)= 1.690, Area= 0.13, %Area= 1.16

Methanol:Ethanol- last test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.496, Area= -0.19, %Area= -1.95

Peak 2: Retention Time (min)= 1.585, Area= 10.07, %Area= 101.95

Student 4:

Methanol:Ethanol- first test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.465, Area= 67.70, %Area= 100.00

Methanol:Ethanol- last test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.710, Area= 196.05, %Area= 100.00

Student 5:

Methanol:Propanol- first test tube (simple distillation)

Peak 1: Retention Time (min)= 1.840, Area= 193.42, %Area= 93.47

Peak 2: Retention Time (min)= 2.425, Area= 13.51, %Area= 6.53

Methanol:Propanol- last test tube (simple distillation)

Peak 1: Retention Time (min)= 2.520, Area= 830.06, %Area= 100.00

Student 6: (My Experiment)

Methanol:Propanol- first test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.640, Area= 105.78, %Area= 94.71

Peak 2: Retention Time (min)= 2.205, Area= 5.90, %Area= 5.29

Methanol:Propanol- last test tube (fractional distillation)

Peak 1: Retention Time (min)= 2.410, Area= 790.25, %Area= 100.00

Student 7:

Methanol:Propanol- first test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.685, Area= 42.94, %Area= 100.00

Methanol:Propanol- last test tube (fractional distillation)

(no peak)

Student 8:

Methanol:Butanol- first test tube (simple distillation)

(no peak)

Methanol:Butanol- last test tube (simple distillation)

(no peak)

Student 9:

Methanol:Butanol- first test tube (simple distillation)

Peak 1: Retention Time (min)= 1.090, Area= 272.21, %Area= 84.34

Peak 2: Retention Time (min)= 2.420, Area= 50.53, %Area= 15.66

Methanol:Butanol- last test tube (simple distillation)

Peak 1: Retention Time (min)= 3.210, Area= 1421.66, %Area= 100.00

Student 10:

Methanol:Butanol- first test tube (fractional distillation)

Peak 1: Retention Time (min)= 1.090, Area= 1.92, %Area= 0.20

Peak 2: Retention Time (min)= 2.070, Area= 2.23, %Area= 0.24

Peak 3: Retention Time (min)= 3.010, Area= 932.02, %Area= 99.56

Methanol:Butanol- last test tube (fractional distillation)

Peak 1: Retention Time (min)= 0.906, Area= 0.25, %Area= 0.13

Peak 2: Retention Time (min)= 1.040, Area= 144.64, %Area= 76.40

Peak 3: Retention Time (min)= 2.435, Area= 44.44, %Area= 23.47

My Boiling Points for Methanol:Propanol (fractional distillation)
1/2 mL of Distillate	test tube 1	tube 2	tube 3	tube 4	tube 5	tube 6	tube 7
0.5	69	74	76	79	81	84	90
1	73	75	77	79	82	85	91
1.5	75	75	78	79	82	86	92
2	74	75	78	80	83	87	92
2.5	74	75	78	81	84	88	93
3	75	75	78.5	81	84	90	74

WORD BANK:

Atomic solids

Body-centered cubic

Boiling point

Condensation

Covalent atomic solids

Crystal lattice

Crystalline solids

Distillate

Distillation

Dynamic equilibrium

Evaporation

Face-centered cubic

Freezing

Freezing point

Ionic solids

Intramolecular

Interionic forces

Intermolecular forces

Liquid State

Macromolecule

Melting

Melting point

Metallic atomic solids

Molar heat of fusion

Molar heat of vaporization

Molecular solids

Non-bonding atomic solids

Non-crystalline (amorphous) solids

Properties of Liquids

Properties of Solids

Simple cubic

Solid State

Sublimation

Surface tension

Surfactants

Vapor pressure

Vaporization

Viscosity

Wetting action

Use the Vocabulary words above to complete the following sentences words can be used more than once, some words are not be used.

d. The molecules of a ________ are in constant motion. e. The __________ of a liquid is related to the shape of the molecules that make up the liquid. f. The force of attraction that causes the surface of a liquid to contract and form a âbeadâ or spherical drop is called? _________ _______ g. Chemical that reduce surface tension are called? __________ h. A liquids ability to spread out evenly over a surface as a thin film is called itâs? _________ _______ i. ____________ is the process by which molecules of a liquid break away and go into the gas phase. j. When the molecules of a volatile liquid jump to gas phase it is called _________. k. The reverse of evaporation (the conversion of a vapor to a liquid) is called? _________ l. When the rate at which the water is evaporating is equal to the rate at which the water vapor is condensing, you have established a __________ _________. m. ________ _______ is the partial pressure of a gas in dynamic equilibrium with its liquid. n. ________ _______ is when the vapor pressure equals the atmospheric pressure. o. Boiling point can be used to purify a solution of two or more substances by ________. p. The condensed vapor sample is called the? ________ q. The exact quantity of heat required to vaporize 1 mole of a liquid at constant pressure and temperature is called the ________ ________ ___ __________. r. In ________________ __________ the particles do not have a definite or regular order (there is no repeating pattern throughout the solid). s. In ____________ __________, the particles are arranged in regular, systematic patterns called a ________ _________. t. The three different types of crystal lattices based on the cube are? ________ ______, _____________ ______, and ___________, ________. u. The three types of atomic solids include _________ _____, ___________ ______, and __________ ________.

CHE 211 Study Guide - Midterm Guide: Lead, Boiling Point, Distillation

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