Question

When a 3.90-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter, the temperature drops from 24.5°C to 19.3°C. Calculate DH (in kJ/mol NH4NO3) for the solution process

NH4NO3(s) ---> NH4+(aq) + NO3-(aq)


Assume that the specific heat of the solution is the same as that of pure water.

Answer 1

q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
q = heat loss by the water in J. Divide by 1000 to convert to kJ. That gives you total kJ. Then kJ/3.90 gives kJ/gram NH4NO3 and
(kJ/3.90)*molar mass NH4NO3 gives kJ/mol.

Answer 2

1305.41
26.78