100.0 mL of 0.100 M HBr at 22.0˚C and 10.0 mL of 1.00 M KOH at 21.0 ˚C are combined in a constant?

... pressure calorimetry experiment and the temperature goes up to 23.1 ˚C. What is ΔHrxn/mol HBr? (Assume calorimeter has negligible heat capacity and the density of the solutions is one g/mL.)

100.0 mL of 0.100 M HBr at 22.0˚C and 10.0 mL of 1.00 M KOH at 21.0 ˚C are combined in a constant pressure calorimetry experiment and the temperature goes up to 23.1 ˚C. What is ΔHrxn/mol HBr? (Assume calorimeter has negligible heat capacity and the density of the solutions is one g/mL