Final answer:
The energy exchanged in a reaction varies with the number and strength of molecular bonds, and the heat capacity is an extensive property that depends both on the type and amount of substance.
Step-by-step explanation:
The amount of energy exchanged in a reaction is indeed a function of the amount of substance being investigated. Major factors that determine this energy are the number of bonds or force pairs and their strength. The amount of energy, or heat Q, required for a phase change in a sample with mass m is related to these factors.
The energy exchanged, whether it is for heating, cooling, or phase changes such as melting (heat of fusion) or evaporating (heat of vaporization), depends on the type of substance due to variations in force strengths and molecular structures, and on the mass of the substance, because larger quantities contain more bonds.
Additionally, the heat capacity, which determines how much energy is needed to change the temperature of a substance, is an extensive property that varies with the type and amount of the substance.