If the heat of combustion for a specific compound is -1230.0 kj/mol and its molar mass is 46.95 g/mol, how many grams of this compound must you burn to release 354.10 kj of heat?

Moles of substance required = (energy required)/(energy per mole) = (-354.10)/(-1230.0) = 0.287886178... moles

Mr = mass/moles so mass = Mr * moles = 46.95 * 0.28... = 13.5162561 = 13.5g (3sf)