### q=-q question (7.39)

Posted:

**Wed Jan 14, 2015 9:31 pm**When asked to solve for the final temperature of "A 50g ice cube at 0C [when] added to a glass containing 400g of water at 45C" (7.39), I plugged in mCT=-mCT to find T

_{f}. I ended up with the answer 42.4C, but the back of the book has the answer as 31C. I noticed from the solution manual that the grams where turned into moles and multiplied by 6.01*10^{3}J/mol^{-1}and added to mCT to calculate the heat of the ice cube. Why is it that the grams were turned into moles and were multiplied by 6.01*10^{3}then they were added to mCT?