The Fermentation of Yeast Phyllings Lerisson Chipola Junior College CHM 2210 Introduction Fermentation is used to make bread and wine. The process of fermentation converts glucose into ethanol and carbon dioxide. In 1810, Gay Lussac discovered the general chemical equation for the breakdown of sugar into ethanol and carbon dioxide: C6H12O6---- 2CH3CH2OH + 2CO2 A chemist by the name of Louis Pasteur discovered that when a combination of spicific salts were incorporated into the process of fermentation, the reaction proceeds at a faster rate; this combination of salts became known as Pasteur’s salts. Pasteur’s salts solution consists of 2.0g potassium phosphate, .2g calcium phosphate, .2g magnesium sulfate, and 10g ammonium tartrate in 860 mL of water. Gay Lussac Louis Pasteur Discovered the general equation for the process of fermentation. Discovered a combination of salts that allowed fermentation to proceed at a faster rate; these salts are named for Purpose The purpose of the experiment is to measure the rate at which the fermentation occurs. The rate can be determined by measuring the amount of carbon dioxide that is present. A carbon dioxide gas sensor and graphing calculator will be used to record the levels of carbon dioxide that result from this experiment. The prediction is made that the presence of Pasteur’s salts will increase the rate of carbon dioxide production. Materials 1 package of yeast Graphing calculator Glucose solution CBL Pasteur’s salts CO2 Gas sensor Distilled water Graduated cylinders Pipettes Plastic bottle Procedure 1. Connect calculator and C B L . Push APPS. Select CO2 gas sensor. 2. Select DATA MATE. Change mode of calculator to TIME GRAPH. 3. Pipette 2mL of distilled H2O and 2mL of glucose solution into a graduated cylinder. (Use separate pipettes for each solution.) 4. Carefully weigh out .05g of dry yeast and put into plastic bottle. To the yeast, add the glucose and distilled H2O. 5. Stopper the bottle with the CO2 gas sensor. Press start on the calculator. When graph is complete, manually record data. Data The Amount of Carbon Dioxide Present in the Fermentation of .05g Yeast RUN 1 4000 Amount of Carbon Dioxide Present (ppm)) 3500 3000 2500 w/ 2mL Pasteur Salts w/ 2ml Water 2000 1500 1000 500 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Time Elapsed (in minutes) Data The Amount of Carbon Dioxide Present in the Fermentation of .05g Yeast RUN 2 Amount of Carbon Dioxide Present (ppm) 6000 5000 4000 w/ 2mL Pasteur Salts 3000 w/ 2mL Water 2000 1000 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Time Elapsed (in minutes) Conclusion In both Run 1 and Run 2, the rate of carbon dioxide production was calculated at 18 minutes: Run 1 When Pasteur’s salts were added to the fermentation process, the carbon dioxide had a production rate of 88.5ppm/min; without the addition of Pasteur’s salts, carbon dioxide had a production rate of only 41.3ppm/min. Run2 When Pasteur’s salts were added to the fermentation process, the carbon dioxide had a production rate of 79.8ppm/min; without the addition of Pasteur’s salts, carbon dioxide had a production rate of 58.7ppm/min. Based on the average results of this experiment, the rate of carbon dioxide production when Pasteur’s salts are present is 1.68 times faster than when Pasteur’s salts are not present. The hypothesis—stated in Purpose—is supported; the addition of Pasteur’s salts does increase the rate of carbon dioxide production. *The levels of Carbon Dioxide Present (ppm) in each Run RUN 1 RUN 2 Time W/Salts W/H2O W/H2O W/Salts 0 841 635 577 508 2 997 704 811 645 4 1124 753 880 684 6 1310 821 958 733 8 1437 860 1036 831 10 1613 929 1153 909 12 1857 1017 1290 1056 14 2141 1114 1496 1212 16 2297 1251 1730 1378 18 2434 1378 2014 1564 Notice, that at time zero (0), the values do not start out at zero. The values do not start out at zero because carbon dioxide is naturally present in the air. Since the experiment could not be carried out inside of a vacuum, carbon dioxide is already present when the experiment first begins. *Only a portion of the spreadsheet is presented.
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