Question

Suppose that stoichiometric amounts of nitrogen gas and hydrogen gas react in a calorimeter to produce 5.00 g of ammonia gas. The calorimeter temperature rises 0.42°C. The calorimeter and water have a combined heat capacity of 32.16 kJ/K. Calculate the heat of formation of ammonia, ΔH°f, in kJ/mol. The formation reaction for ammonia is: 0.5N2(g) + 1.5H2(g) → NH3(g).

Answer 1

Use the specific heat and change in temp of the calorimeter to find the energy released by the reaction.

Find the moles of NH3 formed using the molar mass of ammonia and the mass of product formed.

Divide the energy released by the moles of ammonia formed, and you'll have the heat of formation, in kJ/mol