Specific Heat Capacity and Enthalpy of reaction

[505400967]

I am struggling with conceptualizing this concept:

"If the heat capacity of the reactants is larger than that of the products, the enthalpy of the reactants will increase more sharply with increasing temperature. If the reaction is exothermic, the reaction enthalpy will become more negative."

As I understand it, having a higher heat capacity makes it so that increases in temperature cause a lower change in enthalpy.

[Chem_Mod]

I will give a quick hypothetical example!

If you have A --> B, lets say the heat capacity of A if 5 J/g*K and the heat capacity of B is 1 J/g*K. In this hypothetical, the reactants have a higher heat capacity than the products.

If we then said the overall reaction increases by 2 degrees, that would mean 10 J of enthalpy had to be applied to A (5 J/g*K x 2 K) and 2 J of enthalpy had to be applied to B (1 J/g*K x 2K). Thus, the enthalpy change in the reactants is much greater than that of the products.

In terms of the second part, if a reaction is exothermic, that means the energy that is produced from the bonds form in the products is greater than that of the energy required to go into the reactants to break the bonds. In other words, if you had CD --> EF, lets say it takes 10J to break the bond of CD and 20J are produced from EF bonding, then this is exothermic. The difference here is -10J. If you were to increase the temperature, think back to the first A-->B example. If the temperature raises by 2K, the reactants will go to 20J and the products produce 40J. The difference is now -20J, a greater negative number.