Chapter 6.6, Problem 6.9E

Suppose 33 mL of 1.20 M HCl is added to 42 mL of a solution containing excess sodium hydroxide, NaOH, in a coffee-cup calorimeter. The solution temperature, originally 25.0°C, rises to 31.8°C. Give the enthalpy change, ΔH, for the reaction:

$\text{HCl}(aq)+\text{NaOH}(aq)\to \text{NaCl}(aq)+{\text{H}}_2\text{O}(l)$

Express the answer as a thermochemical equation. For simplicity, assume that the heat capacity and the density of the final solution in the cup are those of water. (In more accurate work, these values must be determined.) Also assume that the total volume of the solution equals the sum of the volumes of HCl(aq) and NaOH(aq).