The chemical equation that describes the fermentation by yeast of simple sugars

Question

The chemical equation that describes the fermentation by yeast of simple sugars (e.g., glucose) into ethanol (EtOH) is:

C6H12O6 ? 2 CH3CH2OH + 2 CO2

Consider an ethanol plant that produces 93 million gallons per year of 100% ethanol.  Starch in corn is broken down into glucose and fermented into ethanol.  Assuming the chemical equation above applies with 100% conversion, how many bushels (bu) of corn are used to produce this amount of ethanol?

Here's some useful information, although you might need to search out some other conversion factors:

Answer tolerance

Explanation / Answer

ethanol vol= 93 x10^6 gallons = 93 x10^6 x 3.7854 = 352.0422 x10^6 liters

ethanol mass = 352.0422 x10^6 x 0.789 kgs

                             = 2.777 x10^11 gm

ethanol moles = mass/molar mass = 2.777 x10^11/46 = 6.037 x 10^9 moles

glucose moles required for ethanol production = 6.037 x10^11 /2 = 3.01848 x10^ 9

glucose mass ( starch mass) = 3.01848 x180 x10^9 = 5.43326 x10^11 gm

corn mass considering 63.1 % is 5.43326 x (100/63.1) x10^11 = 8.610556 x10^11 gm

                                                    = 8.610556 x0.00220462 x10^11 = 1.8983 x10^ 9 lb

                                                      = 1.8983/56   x 10^ 9

                                                      = 3.389822 x10^ 7 bu

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