My question is about heat calculation. I learned that q = mc delta T. Is that only for water? I'm doing a practice problem "100 g of NH3 are cooled from 100 C to 75 C. Heat capacity for ammonia gas 35.1 J/ mol *K. What is heat change?" I plugged in the mass of ammonia but the solution turned it to moles. So is q = mc delta T only for water? Why did the book's answer key convert to moles? Thank you.