Please Help with calcaculate the heat in the system!!!!!!?

Addition of aqueous strong acid to a bleach solution liberates chlorine according to the reaction below.
OCl^–(aq) + Cl^–(aq) + 2H^+(aq) Cl2(aq) + H2O ΔrH = -202 kJ mol^–1

25.0 mL of a solution 0.400 mol L^–1 in both OCl^– and Cl^– was reacted with excess hydrochloric acid. The mass of the solution after mixing was 100 g.

Calculate q(system) in joules

Assume that the temperature change of the vessel in which the experiment is carried out is negligible
Assume that the heat capacity of the mixture is the same as the specific heat capacity of water (4.184 J g^–1 K^–1).