I have a few questions to ask, since I was absent from school and I do not really understand the calorimetry problems.
1) When a 16.9 g sample of NaOH dissolves in 70.0 g of water in a calorimeter, the temperature rises from 22.4*C to 86.6*C. Calculate for Delta H for the process NaOH(s) -> Na(aq) + OH(aq)
2) A 2.5 g sample of zinc is heated, then placed in a calorimeter containing 65.0 g of water. Temperature of water increases from 20.00*C to 22.50*C. The specific heat of zinc is 0.390 J/g*C. What was the initial temperature of the zinc metal sample.
1).
q = Mass H2O x specific heat H2O x delta T
delta H = q/16.9 grams if you want it in Joules/g and that time molar mass NaOH if you want it in Joules/mole.
2)heat lost by Zn + heat gained by water = 0
[mass Zn x specific heat Zn x (Tfinal-TinitialZn)] + [mass water x specific heat water x (Tfinal-Tinital)] = 0
Solve for Tinitial Zn