1. The problem statement, all variables and given/known data I have a general concept inquiry. I was doing some thermal homework, and calculating values of Q in a given cycle. One process was isothermal, however it turned out that Q was not zero, causing me to wonder: How can there be a heat transfer in an isothermal process? 2. Relevant equations 3. The attempt at a solution In an isothermal process the temperature does not change. Looking at the formula, Q=mcΔT, if there is no change in temperature, one would therefore find that Q=O. However, if you look at it from conservation of energy, (ΔU=Q-W), the ΔU is zero for an isothermal process, making Q=W, and thereby concluding that there is a heat transfer. Thus I am confused. Could someone please provide some insight into this?