To vaporize/condense a substance, does the substance have to absorb or release heat?

If you add 10ml of hot water to 10ml of cold water and the change in tempature 8°c calculate how much energy is gained by the cold water

Can someone me with questions 12 and 13 plz.

An excess of lithium oxide undergoes a synthesis reaction with water to produce lithium hydroxide li2o+h2o→2lioh if 1.05 g of water reacted, what is the theoretical yield of lithium hydroxide? a) 5.83 x 10–2 g lioh b) 1.17 x 10–1 g lioh c) 2.79 x 100 g lioh d) 1.40 x 100 g lioh