1. The problem statement, all variables and given/known data What is the final temperature of water if 175 g steam at 150 C loses 423 KJ of energy? 2. Relevant equations Q = M *C_p * Δ T Q = m * heat of (phase_change) 3. The attempt at a solution This is how I would go about solving this problem. Going from steam to water requires energy of two types: Going from steam to water --> Q = m * heat of vap Cooling from 150C to 100C --> Q = m * Specific heat of steam * Δ T Furthermore, we are told that steam is finally in the form of water, which has an unknown final temperature, so we have Q = m * specific heat of water * ΔT Add them together, and equates with the heat loss (which is given) - 423KJ = Q (from steam to water) + Q (cooling from 150 to 100) + Q (cooling from 100 to unknown final temperature) Is this correct? If it is, my question would be: is it also correct to make Q (from steam to water) negative? I don't remember seeing heat of condensation. Can I make heat of evaporation negative in this case? Anything else needs to be negative also? Thank you.