QuestionWhen a solid dissolves in water, heat may be evolved or absorbed. The heat of dissolution (dissolving) can be determined using a coffee cup calorimeter.
In the laboratory a general chemistry student finds that when $\mathbf{3 . 6 8} \mathrm{g}$ of $\mathbf{N H}_{4} \mathbf{C l}(\mathrm{~s})$ are dissolved in $\mathbf{1 0 9 . 6 0 ~ g ~ o f ~}$ water, the temperature of the solution drops from 22.47 to $20.09^{\circ} \mathrm{C}$.
The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be $1.84 \mathrm{~J} /{ }^{\circ} \mathrm{C}$.
Based on he student's observatic calculate the enthalpy of dissolution of $\mathbf{N H}_{4} \mathbf{C l}(\mathrm{~s})$ in $\mathrm{kJ} / \mathrm{mol}$.
Assume the specific heat of the solution is equal to the specific heat of water. $\Delta H_{\text {dissolution }}=$ $\square$ $\mathrm{kJ} / \mathrm{mol}$