1. The problem statement, all variables and given/known data A 500 g copper block at 80 C is dropped into 1.0 kg of water at 10 C. Find the entropy change of the system. 2. Relevant equations dS= integral of dQ/T 3. The attempt at a solution I found that the final equilibrium temperature is 290 K using the equation [(m1*c1*dT1) + (m2*c2*dT2)]/ [(m1*c1) + (m2*c2)] I know that this is correct, but I'm not sure what to do from here. I know that this is Tf, but what do I use as Ti for the integral, the temperature of the block or the water? And which equation do I integrate to find the entropy in this case (What is the equation for Q)?