A 100. mL sample of 0.200 M aqueous hydrochloric acid is added to 100. mL of 0.200 M aqueous ammonia in a calorimeter whose heat capacity (excluding any water) is 480. J/K. The following reaction occurs when the two solutions are mixed.

HCl(aq) + NH3(aq) ? NH4Cl(aq)

The temperature increase is 2.34°C. Calculate ?H per mole of HCl and NH3 reacted.

A. 485 kJ/mol

B. -1.96 kJ/mol

C. 154 kJ/mol

D. 1.96 kJ/mol

E. -154 kJ/mol