In the following experiment, a coffee-cup calorimeter containing 100. rm mL of rm H_2O is used. The initial temperature of the calorimeter is 23.0 rm ^{circ}C. If 5.10 g of rm CaCl_2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heat of solution, Delta H_{rm soln}, of rm CaCl_2 is rm -82.8~kJ/mol.