Question

Ethanol, C2H5OH, MW = 46.1 g/mole, is a popular alternative to hydrocarbon fuels. Calculate the grams of ethanol that must be burned to provide 4082 kJ of heat.

Answer 1

C2H5OH + 3O2 ==> 2CO2 + 3H2O
Look up delta H for the combustion.
Then DHcmb x (#g/46.1) = 4,082,000.
Solve for #grams.