Experiment #2

Chem 272

INTRODUCTION AND BACKGROUND

In the biosynthesis of ethanol, sucrose (C12H22O11) is hydrolyzed to fructose (C6H12O6) and glucose (C6H12O6) by yeast, which contains invertase, an enzyme. The monosaccharides are then catalyzed by zymase. Zymase is a collection of enzymes that are found in yeast and catalyze the individual steps in converting glucose and fructose to ethanol and carbon dioxide. · Pasteur's salt solution is added to increase yeast growth and also to help the fermentation. In the reaction, the ethanol formed is used to kill the yeast cells and hinder the fermentation process.

The ethanol that is produced can never reach 100% pure ethanol. A mixture of 95% ethanol and 5% water is the highest concentration that can be obtained by the fractional distillation process. In order to produce 100% ethanol solution, the ethanol must be dehydrated after it is distilled. Ethanol, or dehydrated alcohol, by definition is not less than 99.4% alcohol by volume and not more than 100% alcohol by volume with a boiling point of 780C.

Moonshiners use this process of fermentation hindrance by yeast cells to produce high concentrations of ethanol and increase the price of selling the alcohol. Beer and wine producers also use this method, but do not fractionally distill the solution, allowing only 12% by volume alcohol production.

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