Question

A student dissolves $12.6 \mathrm{~g}$ of ammonium chloride $\left(\mathrm{NH}_4 \mathrm{Cl}\right)$ in $250 . \mathrm{g}$ of water in a well-insulated open cup. She then observes the temperature of the water fall from $20.0^{\circ} \mathrm{C}$ to $16.8^{\circ} \mathrm{C}$ over the course of $4.8$ minutes.
Use this data, and any information you need from the ALEKS Data resource, to answer the questions below about this reaction:
$\mathrm{NH}_4 \mathrm{Cl}(s) \rightarrow \mathrm{NH}_4^{+}(a q)+\mathrm{Cl}^{-}(a q)$
You can make any reasonable assumptions about the physical properties of the solution. Be sure answers you calculate using measured data are rounded to the correct number of significant digits.

Note for advanced students: it's possible the student did not do the experiment carefully, and the values you calculate may not be the same as the known and published values for this reaction.
$\begin{tabular}{|l|l|} \hline Is this reaction exothermic, endothermic, or neither? & endothermic \\ \hline If you said the reaction was exothermic or endothermic, calculate the amount of heat that was released or absorbed by the reaction in this case. \\ \hline Calculate the reaction enthalpy [tex]\Delta \mathrm{H}_{\mathrm{rxn}}$ per mole of $\mathrm{NH}_4 \mathrm{Cl}$. & $\mathrm{kJ}$ \\ \hline \end{tabular}[/tex]
exothermic