When $100$ mL of $0\mathrm{.}200$ M NaCl$($aq$)$ and $100$ mL of $0\mathrm{.}200$ M AgNO$3($aq$),$ both at $21\mathrm{.}9\backslash$deg C$,$ are mixed in a coffee cup calorimeter, the temperature increases to $23\mathrm{.}5\backslash$deg C as solid AgCl forms. What is Hrxn$?$ Answer in kJ$/$mol$.$ Ag$++$ Cl$--->$ AgCl