Lab 4 Write-up- Fermentation and Distillation of Ethanol PDF

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Fermentation and Distillation of Ethanol Introduction: This experiment is used to show how we can use fermentation to create this that we use today, such as ethanol. We drink ethanol as a form of alcohol. By doing this, water is mixed with sucrose and yeast to form ethanol and carbon dioxide (Berg, 2007). Then let it rest so the yeast can be activated and work its magic. This technique is called Fermentation. To separate the ethanol from the fermentation step, you use the technique Distillation. Distillation is a process of separating products by use of evaporation or condensation (Duffy, 1995). This portion is critical because we are basing this part off of the boiling points we know for each compound. This lab teaches us that what we use every day has to go through the techniques so that we can grab the essential items right off the shelves at our home goods stores. Reaction Mechanism:

+ Sucrose

+

Yeast



Water

Ethanol

Equation 1: Sugar → Alcohol + Carbon Dioxide Equation 2: C12H22O11+ H2O → 4CH3CH2OH + 4CO2 Table 1: Chart of all chemicals used in the experiment

Compound/ Formula

Physical Properties

Molecular Weight

Sucrose

C12H22O11 White Solid MP 190-192°C

Ethanol

C2H6O

Amount

Hazards

342.29 g/mol 1.59 g/cm³

30g

Combustible at high temperature

46.07 g/mol

0.789 g/mL

(product) Flammable, toxic to blood

274.3 g/mol

1.1126 g/ml

3g

bacteria

18.01 g/mol

997 kg/cm3

150 mL

Basic

Colorless Liquid BP 78°C

Yeast

C19H14O2 Tan solid particle

Water

H2O BP: 100°C

Density

Procedure: Part Fermentation: Add 30g of sucrose and 150 mL of water to a 250 mL Erlenmeyer flask and stir to dissolve the sucrose. After dissolved, add 3g of yeast to the Erlenmeyer flask and swirl to mix the yeast with the solution. Fill the plastic air lock to the marks that indicated half full and place the stopper to keep the air out and place in a safe, secure place. Essential to be airlocked so the air can’t leave and to allow excess Carbon dioxide to escape. Ethanol will produce in the anaerobic conditions within the flask and the fermentation will being in an hour after being settled. Part Distillation: Assemble the distillation apparatus using the 14/20 glassware that the TA will provide. This should be a collection of a 50 mL Kjeldahl shaped flask, 100 mL Kjeldahl flask, distilling column, connecting adapter, water jacketed condenser, vacuum adapter, and thermometer. Make sure all the clamps and coverings are used. Add 60 mL of the fermentation solution to a 100 mL flask and add a small spin vane. Attacked flask to apparatus and apply the water in and out condenser. Control water flow and make sure using cold water. Heat up the flask to begin distillation of the ethanol to maximize the ethanol content of distillate. To keep the heat in the flask, apply aluminum foil wrap and then a wet paper towel up the tube. This will create and influx of heat inside. Record temperature thoroughly with each reading clear with the reflux line and collection of the distillate. Collect about 2-3 mL of the distillate into a 50 mL flask. Transfer the distillate into a labeled vial and submit the sample to the TA for further testing. Using an Eppendorf pipette (0.897 mL) to measure out an exact volume of the distillate and weigh this solution on an analytical balance. Record the weight, calculate the density, and estimate the % ethanol composition from the density. Results: Thermometer Temperature: - 85°C = 1mL of distillate - 98°C = 1.5 mL - 105°C = 2 mL - 110°C = 2.5 mL Weight of Ethanol: - 0.877 mL collected Estimate % Ethanol composition - 15% (0.877mL/0.897mL) Discussion: When doing this experiment, it was a two step process. One day was to set up the fermentation portion and then let it sit for a whole week. The next lab session we continued the experiment with the next step. This step was for dilution purpose to see how much product we have collected from the fermentation solution. What we got was a good amount of liquid. What the problem we had was the % ethanol composition. When we recovered how much we got

back in ethanol from water, we only got back 15% of the ethanol composition. This means we had an error while either transferring the liquid from the fermentation flask, or we didn’t set up the experiment right. This did cause some confusing because the ethanol started evaporating at the boiling point of ethanol itself. Increasing the temperature to continue boiling did help push through getting the collection of the distillate. Overall this was a great experiment to understand how fermentation works. Works Cited: Daniel Q. Duffy, Stephanie A. Shaw, William D. Bare, Kenneth A. Goldsby. More Chemistry in a Soda Bottle, A Conservation of Mass Activity. Journal of Chemical Education. August 1995, pages 734-736. Halterman, R. Morvant, M. 2017. Organic Chemistry Laboratory Manual. University of Oklahoma, 2017, p. 36-39 Jeremy M. Berg, John L. Tymoczko and Lubert Stryer, Biochemistry, 6th edition, W.H. Freeman and Company, 2007, pages 205-237....