Chemistry Question

Question

When methanol, CH3OH, is burned in the presence of oxygen gas, O2, a large amount of heat energy is released, as shown in the combustion reaction:

CH3OH(g) + 3/2 O2(g) ⟶ CO2(g) + 2 H2O(l) Δ𝐻 = -764kj

Based on the balanced thermochemical reaction, how much heat is produced when 32.8 g of methanol reacts with 50.8 g of oxygen?

Answer 1

moles CH₃OH present = 32.8 g x 1 mol/32 g = 1.025 moles

moles O₂ present = 50.8 g x 1 mol/32 g = 1.59 moles

Limiting reactant = CH₃OH according to the stoichiometry of 1 mol CH₃OH : 1.5 mol O₂

764 kJ/mole CH₃OH x 1.025 moles CH₃OH = 783 kJ heat produced