The quantity of 36.4 kJ/g is the heat of reaction. This is the heat added or the heat liberated when the reaction proceeds. When it is heat added it is usually reported as +36.4 kJ/g. When it is heat liberated or released, it is usually reported as -36.4 kJ/g. The heat of reaction is dependent on the amount of reactant used. Therefore, we can say that the heat of reaction is an intensive property, being that it depends on the amount in the system.
To know the amount of reactant used, we use the approach of dimensional analysis. In this technique, like units are cancelled when they appear in both the numerator and the denominator side. This technique helps us get to the final units of the asked parameter. For this problem, we have to end up with units of grams. The solution is as follows
1,220 J * 1 kJ/1000 J * 1 g / 36.4 kJ = 0.03352 g
Therefore, it needs 0.03352 g of reactant to liberate 1,220 J of heat.
