Question

Saccharomyces cerevisiae produces ethanol by fermentation. The theoretical yield of ethanol from
2.5 g of glucose is ______________ g.

Answer 1

The answer is 50.3% yield, that is 1.25 g.

Explanation

The equation for the reaction is -

C6H12O6→ 2C2H5OH + 2CO2

Now 2.5 g glucose results in

1 mole of C6H12O6 and 2 moles of C2H5OH

1 mole of C6H12O6/180.156 g of C6H12O6 * 2 mole C2H5OH/ 1 mole C6H12O6

= 0.017754 mole C2H5OH

Now, 0.017754 mole C2H5OH  ( 56.808 g C2H5OH/ 1 MOLE C2H5OH) = 1.27865 G C2H5OH.

Now, Actual / theoretical =  (1.279 g C2H5OH/2.5g C2H5OH) * 10² = 50.3% yield, that is 1.25 g.