help with chem please

Question

When methanol, CH3OH,CH3OH, is burned in the presence of oxygen gas, O2,O2, a large amount of heat energy is released. For this reason, it is often used as a fuel in high performance racing cars. The combustion of methanol has the balanced, thermochemical equation

CH3OH(g)+32O2(g)⟶CO2(g)+2H2O(l)Δ𝐻=−764 kJCH3OH(g)+32⁢O2⁡(g)⟶CO2⁢(g)+2⁢H2O(l)⁢Δ⁢H=−764 kJ

How much methanol, in grams, must be burned to produce 511 kJ511 kJ of heat?

Answer 1

for this problem we need to convert 511 kj to grams of methanol. we will use the deltaH of the reaction as a conversion factor because we know that for every 1 mole of ethanol 764 kJ of heat is released

511kJ X (1 mol ethanol/ 764 kJ) X (46.07 g ethanol/1 mol)= 30.8 g