When 0.400 kg of water at 300C is mixed with 0.150 kg of water at 250C contained in a calorimeter, the final temperature is found  to be 270C , find the water equivalent of the calorimeter.

Water of mass m1 = 0.150 kg is taken in the calorimeter at temperature T1 = 250C is mixed with N another known mass of pure water m2 = 0.400 kg at a temperature T2 = 300C and final temperature is found to be T = 270C. Let sw and W be the heat capacity of water and the water equivalent of the calorimeter.Heat gained by (water + calorimeter) at temperature T1 = Heat lost by water at temperature T2i.e., m1sw(T-T1)+Wsw(T-T1) = m2sw(T2-T)     or    W = m2(T2-TT-T1)-m1Hence, W = 0.400 kg [300C-270C270C-250C] - 0.150 kg                 = 0.450 kg