1. The problem statement, all variables and given/known data When using the equation Q=mcΔT for the substance being tested is it the mass of the substance or the mass of the substance + mass of water. 2. Relevant equations 3. The attempt at a solution So when I solve calorimetry problems, I usually find Qwater. Then I set Qsubstance=-Qwater. But then I have to use mcΔT, I'm not sure if it's the mass of the substance or the mass of the substance + mass of the water because I've gotten a few questions wrong and the textbook briefly mentioned the sum of masses but gave no examples. Thanks for your input.