# Considering the following reactions, what type of reaction is represented by these two examples?

## $M g \left(s\right) + \frac{1}{2} {O}_{2} \left(g\right) \to M G O \left(s\right) + 146$ kcal/mol ${H}_{2} \left(g\right) + \frac{1}{2} {O}_{2} \left(g\right) \to {H}_{2} O \left(g\right)$ $\Delta H = - 57.82$ kcal/mol.

These are both $\text{enthalpies of formation}$, $\Delta {H}_{f}^{\circ}$
The $\text{enthalpy of formation}$ is the enthalpy associated with the formation of one mole of product from its constituent elements under standard conditions.
Note that you have listed enthalpy as a product in the formation of $M g O$; of course you are aware that this represents a NEGATIVE $\Delta {H}_{f}^{\circ}$. If you ar not clear on why I should mention this, ask for clarification.