1. The problem statement, all variables and given/known data There are 2 kg of water in an aluminium pot at the temperature of 30C. What is the mass of water vapor (100C) needed to heat the pot with water to 60C? Mass of the pot = 0.5kg m(water)=2kg m(pot)=0.5kg T1=30C T2=60C c(water)=4200 J/kg*C c(aluminium)=890 J/kg*C T(water vapor)=100*C c(water vapor)= 2020 J/kg*C m(water vapor)=? 2. The attempt at a solution Q=Q1+Q2 Q=c(water)*m(water)*(T2-T1)+c(aluminium)*m(aluminium)*(T2-T1) I supposed that Q=c(vapor)*m(vapor)*(T2-T(vapor)) But then Q would be less than 0 since the temperature difference is less than 0. What is the right way to write this last equation? And the final equation to find the mass of water vapor? Thank you!