[SOLVED] please explain this entropy change formula for me?? An aluminum bar of mass 2.00 kg at 300 Celsius is thrown into a lake. The temperature of the water in the lake is 15.0Celsius; the specific heat capacity of aluminum is 900 J/(kg*K). The bar eventually reaches thermal equilibrium with the lake. What is the entropy change DeltaS_lake of the lake? Assume that the lake is so large that its temperature remains virtually constant.