1. What mass of carbon is required to produce 100kj of heat, when burned in air? Enthalpy change = -392kj.

2. What mass of methanol is required to produce 1000kj of heat, when burned in air?

2 answers

C + O2 ==> CO2
392 kJ/mol x ? mol = 100 kJ
Then ?mol = grams/molar mass. You know mol and you know molar mass; solve for grams.
Got it - thank you.