Abstract: Fermentation of sucrose with brewer yeast catalyst was successfully conducted to yield ethanol with 70.2 % conversion of sucrose. Based on the graph of Refractive Index vs % ethanol (v/v), 32.8% of ethanol was determined to be in the distillate solution with corresponding Refractive Index of 1.3555
Statement and purpose
The purpose of this experiment was to determine the % of ethanol (v/v) in the resulting solution and the % conversion of sucrose
Introduction
The fermentation 17.1 g of sucrose was successfully conducted by added 5.0 g of brewer yeast, 17.1 g sucrose and 100mL deionized water in a flask. After 1 week, the ethanol solution was distilled and collected. The reaction was demonstrated as below:
C12H22O11 (s) + H2O (l) …show more content…
This value was neither RI of ethanol or water. According to the true RI values, RI of ethanol is 1.3616 (Ref. 4), and the RI of water is 1.3333 (Ref.5). As mention in the lab manual (Ref. 1), the alcohol would be removed in the first 15-20% of the distillate; thereafter, just water would distill over. Since solution had the volume of 100mL, the ethanol should have been removed before the distillate reached 25 mL. This was the reason why 25 mL was used to determine the amount of converted ethanol. Only 32.8 % of ethanol was determined to be in the solution because of maximum amount of alcohol could be produced in fermentation is 12-14%. As the amount of alcohol, in this case ethanol, get higher, the process will stop due to the denaturing of yeast cells, in according to the lab manual (Ref. 1) The RI of the solution contained ethanol was slightly below the true RI of ethanol due to the fact that the solution must have contained some water that was distilled over and caused the RI of the solution to slightly go …show more content…
Based on the graph of Refracted index vs %ethanol v/v (Ref. 1), 32.8% of ethanol was determined to be in the ethanol solution. Additionally, 70.2% conversion of sucrose was determined. The RI of the solution was determined to be 1.3555. This RI was slightly lower than true RI of ethanol because the solution must have contained water which lowered the RI of the solution.
Post lab Question
1. We only need 25mL of distillate to determine total amount of ethanol because most of the alcohol will be removed in the first 15-20% of the distillate, only water will distill over after that. Because 25mL of more than 100mL of solution is more than 20% of distillate, so most of the alcohol is expected to be collected.
2. Even if we use more sugar, we still cannot achieve 90% ethanol solution. The maximum amount of alcohol which can be produced during the fermentation is around 12-14% because as the alcohol content get higher, the yeast culture will die and the fermentation process will be stopped
3. If carbon dioxide, the gas product of the fermentation, was to react with calcium hydroxide instead of water, a precipitate CaCO3 will form. The reaction would happen as follow:
Ca(OH)2 (l) + CO2 (g) → CaCO3 (s) + H2O
Statement and purpose
The purpose of this experiment was to determine the % of ethanol (v/v) in the resulting solution and the % conversion of sucrose
Introduction
The fermentation 17.1 g of sucrose was successfully conducted by added 5.0 g of brewer yeast, 17.1 g sucrose and 100mL deionized water in a flask. After 1 week, the ethanol solution was distilled and collected. The reaction was demonstrated as below:
C12H22O11 (s) + H2O (l) …show more content…
This value was neither RI of ethanol or water. According to the true RI values, RI of ethanol is 1.3616 (Ref. 4), and the RI of water is 1.3333 (Ref.5). As mention in the lab manual (Ref. 1), the alcohol would be removed in the first 15-20% of the distillate; thereafter, just water would distill over. Since solution had the volume of 100mL, the ethanol should have been removed before the distillate reached 25 mL. This was the reason why 25 mL was used to determine the amount of converted ethanol. Only 32.8 % of ethanol was determined to be in the solution because of maximum amount of alcohol could be produced in fermentation is 12-14%. As the amount of alcohol, in this case ethanol, get higher, the process will stop due to the denaturing of yeast cells, in according to the lab manual (Ref. 1) The RI of the solution contained ethanol was slightly below the true RI of ethanol due to the fact that the solution must have contained some water that was distilled over and caused the RI of the solution to slightly go …show more content…
Based on the graph of Refracted index vs %ethanol v/v (Ref. 1), 32.8% of ethanol was determined to be in the ethanol solution. Additionally, 70.2% conversion of sucrose was determined. The RI of the solution was determined to be 1.3555. This RI was slightly lower than true RI of ethanol because the solution must have contained water which lowered the RI of the solution.
Post lab Question
1. We only need 25mL of distillate to determine total amount of ethanol because most of the alcohol will be removed in the first 15-20% of the distillate, only water will distill over after that. Because 25mL of more than 100mL of solution is more than 20% of distillate, so most of the alcohol is expected to be collected.
2. Even if we use more sugar, we still cannot achieve 90% ethanol solution. The maximum amount of alcohol which can be produced during the fermentation is around 12-14% because as the alcohol content get higher, the yeast culture will die and the fermentation process will be stopped
3. If carbon dioxide, the gas product of the fermentation, was to react with calcium hydroxide instead of water, a precipitate CaCO3 will form. The reaction would happen as follow:
Ca(OH)2 (l) + CO2 (g) → CaCO3 (s) + H2O