If you have a balanced equation you can convert between mass and energy using dimensional analysis.

Calculate the heat associated with the decomposition of 1.15g of NO_{2}(g) according to the equation:

N_{2}(g) + 2O_{2}(g) → 2NO_{2}(g)
ΔH = +67.6 kJ

Try this one on your own:

Calculate the mass of ethane, C_{2}H_{6}, which must be burned to produce 100kJ of heat.

2C_{2}H_{6}(g) + 7O_{2}(g) → 4CO_{2}(g) + 6H_{2}O(l) ΔH = -3120kJ

Is this reaction endothermic or exothermic?