30.0 mL of 2.0 M NH3(aq) at 21.0°C is mixed with 30.0 mL of 2.0 M HCl(aq) at 21.0°C in a calorimeter. As the reaction
proceeds, the temperature rises to 33.56°C. Assume the
densities of the solutions are both 1.00 g/mL and the specific
heats are 4.18 J/gºC. Calculate the enthalpy change (AH) of
the reaction in KJ.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%