Ethanol from Sucrose - Franko Piskulich Chemistry 212 May...

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Franko Piskulich Chemistry 212 May 7, 2010 Lab: 17 Ethanol from Sucrose Purpose The purpose of performing this experiment is to produce ethanol from sucrose. The fermentation processes involved in making bread, making wine, and brewing are among the oldest chemical arts. In 1897, Buchner demonstrated that yeast extract would bring about alcoholic fermentation in the absence of any yeast cells. The fermenting activity of yeast is due to a remarkably active catalyst of biochemical origin, the enzyme zymase. It is now recognized the most of the chemical transformations that go on in living cells of plants and animals are brought about by enzymes. The enzymes are organic compounds, generally proteins, and establishment of structures and reaction mechanisms of these compounds is an active field of present-day research. Zymase is now known to be a complex of at least 22 enzymes, each of which catalyzes a specific step in the fermentation reaction sequence. Procedure Fermentation Place 2.00 g of sucrose in a 50-mL Erlenmeyer flask. Add 18 mL of water warmed to 25-30 o C, 2.0 mL of Pasteur’s salts, and 0.2 g of dried baker’s yeast. Shake the contents vigorously to mix them, and then attach the balloon directly to the Erlenmeyer flask. The gas will cause the balloon to expand as the fermentation continues. Oxygen from the atmosphere is excluded from the chemical reaction by this technique. As long as carbon dioxide continues to be liberated, ethanol is being formed. A solution of Pasteur’s salts consists of potassium dihydrogen phosphate, 1.0 g; calcium phosphate (monobasic), 0.10
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Ethanol from Sucrose - Franko Piskulich Chemistry 212 May...

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