When a $6\mathrm{.}50$ g sample of solid sodium hydroxide dissolves in $100\mathrm{.}0$ g of H$2$O in a coffee cup calorimeter, the temperature rises from $21\mathrm{.}6\backslash$deg C to $37\mathrm{.}8\backslash$deg C$.$ Calculate H $($in kJ$/$mol$)$ for this process.