An Example, the Production of Ethanol from Sugar

Example 16.1 Estimate the equilibrium constant for the conversion of sugar (sucrose) to ethanol at 25°C= 298.15 K. The overall reaction is 

The extreme value (K= 10 ) suggests that if you dropped some water in your sugar bowl and equilibrium occurred in 

A is the correct overall chemical description of a reaction that is carried out on a massive industrial scale to make ethanol for motor fuels (Brazil produces about 25 billion pounds a year), and on a small scale in thousand of breweries, wineries, moonshine operations and home beer and wine operations (most often using cheaper impure sugar or starch sources, like grapes, barley or com). But we only know how to carry it out in aqueous solution, with the aid of living cells (mostly yeasts in commercial practice, some others in laboratory settings). Any reaction with K= 10 is practically irreversible, so this calculation tells us that it should be possible to conduct the reaction (which most of us already knew) but little else. 

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