Distillation of Ethanol from Alcoholic Beverage

Objectives- Separate the components of alcoholic beverage using distillation

- Construct a distillation curve

- Calculate the percent ethanol in the alcoholic beverage

- Compare the efficiency of simple and fractional distillation in separating liquid mixture

Distillation- process of heating a liquid until its more volatile constituents pass into the vapor phase, and then cooling the vapor to recover such constituents in liquid form by condensation.

- the main purpose of distillation is to separate a mixture of several components by taking advantage of their different volatilities, or the separation of volatile materials from nonvolatile materials.

-it is a physical separation process, and NOT a chemical reaction.

Types of Distillation

Simple distillation - use to separate mixtures of liquids with significant difference involatility

Fractional distillation - used when components of a mixture have close boiling points

Steam distillation - the process of separating or purifying a liquid by passing steamthrough it

Vacuum distillation - distilling liquid at low pressure so that it boils at a lower boiling point

Simple Distillation Set up4

1. Distilling flask

2. Distilling head3

3. Pocket Thermometer 4. Thermometer

2 7 1

5

5. Condenser

6. Cooling water in6 8

7. Cooling water out 8. Adapter9

9. Receiving flask

Fractional Distillation Set up1. Distilling flask5

2. Fractionating column 3. Distilling head8

4

4. Pocket Thermometer7 6 9

3

5. Thermometer 6. Condenser 7. Cooling water in 8. Cooling water out10

2

9. Adapter

1

10. Receiving flask

Boiling Point- temperature at which the vapor pressure equals the atmospheric pressure

- temperature at which the vapor pressure of a liquid slightly exceeds the pressure of the atmosphere above the liquid- characterized by vigorous bubbling and churning of the liquid as it vaporizes

- varies significantly with changes in pressure

Effect of PressureDaltons Law of Partial Pressure- the sum of the partial pressures of all the gases equals the totalpressure

PT = P1 + P2 + P3 +

Raoults Law- For liquid mixtures, the partial pressure of liquid A (PA) is equal to the vapor pressure of the pure liquid A (PA) multiplied by its mole fraction (XA) in the mixture PA = XAPA- For mixture of liquid A and B,

PT = PA + PB = XAPA + XBPB

Liquid-Vapor Phase DiagramBoiling point of pure B Vapor composition line

Liquid composition line

Boiling point of pure A

Liquid-Vapor Phase Diagram

ApplicationLiquid-Vapor Phase Diagram100

T E M P E R A T U R E

90

80

100 A

80 A 20 B

60 A 40 B

40 A 60 B

20 A 80 B

100 B

COMPOSITION (%)

ApplicationLiquid-Vapor Phase Diagram100

T E M P E R A T U R E

90

80

100 A

80 A 20 B

60 A 40 B

40 A 60 B

20 A 80 B

100 B

COMPOSITION (%)

Methodology15 mL of test sample + boiling chips distillStop when: * the temperature reaches 100C * the volume of the sample remaining in the flask is approximately 1-2 mL

DISTILLATE- Collect 0.5 mL using the calibrated test tubes - Record the temperature for each fraction collected - Perform flammability test

RESIDUE- Measure volume remaining in the flask

Precaution: have the set up check before starting the distillation proper never add boiling chips when the distillation has started the sample will boil over if the heat is not regulated make sure that the calibrated test tubes are clean and dry

Data and ResultsTest tube1 1 2 3 4 5 6 7 8 9 10 11 12 13

mL 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 7.0

Temp

Confirmatory test

Get the volume of the distillate that willtest positive with the flammability test

Compute the percent ethanol in yoursample Volume of ethanol % ethanol =x 100

Volume of sample

Measure the volume of sampleremaining in the flask, and add it to the total volume of the distillate (Vaccounted)

Compute the percent loss% loss = Vol of sample - Vaccounted x 100 Volume of sample

Data and ResultsDISTILLATION CURVE

TEMPERATURE

VOLUME OF DISTILLATE

Data and ResultsSimple Distillation Curve

Data and ResultsFractional Distillation Curve

Data and ResultsEfficiencyGROUP1 2 3 4 5 6 7 8 9 10

SAMPLE

% EtOH(Actual)

TYPE

% EtOH(Experimental)

Fractional DistillationFRACTIONATING COLUMN

Fractional DistillationEFFICIENCY - refers to how well a fractionating column can separatecomponents of a liquid mixture

- depends on:Length Packing material Reflux ratio

- reported in theoretical plates

Fractional DistillationTheoretical Plates- is the number of steps needed to bring about a specifieddegree of separation of two components in a mixture.

Fractional DistillationTheoretical PlatesNUMBER OF THEORETICAL PLATES NEEDED TO SEPARATE A BINARY MIXTURENumber of TP 1 5 10 50 100 Approx. bp difference (oC) 100 35 20 4 2

Fractional DistillationTheoretical PlatesCHARACTERISTICS OF SOME FRACTIONATING COLUMNType of column Holdup (mL) 1.5 5 9 0.2Theoretical Plates (TP)

Height of Each TP (cm) 8 4 4 0.4-2

Separable Bp diffrnce (oC) 50 30 30 3-20

Vigreux Glass helices Metal sponge Spinning band

3 6 6 11-61

Azeotropes- is a mixture of two or more solvents in such a ratio that its compositioncannot be changed by simple distillation

- when boiled, the resulting vapor has the same ratio of constituents as theoriginal mixture of liquids

- also known as constant boiling mixtures

AzeotropesTypes of Azeotropes:POSITIVE AZEOTROPES - also called minimum boiling mixture - boils at a lower temperature than anyother ratio of its constituents

- strong intermolecular attraction withsimilar molecules

azeotrope

Example: 95.6% ethanol / 4.4% waterBptetOH = 78.4C Bptwater = 100C Bptazeotrope = 78.1CBoiling point of liquid Mr. A. R. M. Salcedo Vapor composition

AzeotropesTypes of Azeotropes:NEGATIVE AZEOTROPES - also called maximum boiling mixture - boils at a higher temperature than anyother ratio of its constituentsazeotrope

- strong intermolecular attraction withdifferent molecules

Example: 20.2% hydrogen chloride / 79.8% waterBptHCl = -84C Bptwater = 100C Bptazeotrope = 110CBoiling point of liquid Mr. A. R. M. Salcedo Vapor composition