Question

Synthesis of Ethanol by Fermentation Lab question:

Describe and explain the possible effect on your results of the following experimental errors or variations. a) you forgot to add the pasteur's salts b) during the fractional distillation you continued to collect distillate until the temperature reached 98 degrees C. c) unknown to you someone reset the automatic pipet for the density determination to 190 μL.

Answer 1

a)

Yeast converts the sugar to alcohol. For yeast, a specific buffer region is maintained. This can be achieved by adding Pasteur's salt.

So, if you for get to add the Pasteur's salt, the proteins in the yeast do not become denatured. So, the % of ethanol decreases.

b)

At higher temperature, other side products( like water )are also collected along with alcohol. So, it give impure alcohol.

C)

Change in density gives errors in calculations of amount of alcohol.