Chapter 6, Problem 17PE

Two oxides of copper can be made from copper by the following reactions.

$\begin{array}{l}2\text{Cu}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to 2\text{CuO}\left(s\right)\Delta H°=-310\text{ kJ}\\ \text{2Cu}\left(s\right)+\frac{1}{2}{\text{O}}_{\text{2}}\left(g\right)\to {\text{Cu}}_{\text{2}}\text{O}\left(s\right)\Delta H°=-169\text{ kJ}\end{array}$

Using these data, construct an enthalpy diagram that can he used to find $\Delta H°$ for the reaction ${\text{Cu}}_{\text{2}}\text{O}\left(s\right)+\frac{1}{2}{\text{O}}_{\text{2}}\left(g\right)\to 2\text{CuO}\left(s\right)$. Is the reaction endothermic or exothermic?

(Hint; Remember, an arrow points down for a negative $\Delta H°$ and up for a positive $\Delta H°$.)