What is the pH of a buffer that results when 0.50 mole of H3PO4 is mixed with 0.25 mole of NaOH and diluted with water to 1.00 L? (The acid dissociation constants of phosphoric acid are Ka1 = 7.5 x 10^-3, Ka2 = 6.2 x 10^-8, and Ka3 = 3.6 x 10^-13)

4.25g sample of solid ammonium nitrate dissolves in 60.0g of water in a coffee-cup calorimeter, the temperature drops from 22.0 c to 16.9 c. assume that the specific heat of the solution is the same as that of pure water. calculate delta(h) (in kj/mol nh4no3) for the solution proces.