Question

the heat of combustion of methane is _880kj mol if 3.2 of methane is burnt

Answer 1

The molar mass of methane is 16.04 g/mol.

40g methane x 1 mol/16.04g = 2.49 moles of methane.

This reaction, the combustion of methane, has a reaction enthalpy change of -882.0 kJ/mol (Methane (data page) - Wikipedia), meaning that it gives off 882.0 kJ of heat when one mole is combusted.

With simple stoichiometry, we can determine that -882.0 kJ/mol x 2.49 mol CH4 = 2.20 x 10^3 kJ released.