When a sample of 28.54 g NH₄NO₃ dissolves in 56.4 g of water, and the temperature changes from 25.27°C to 8.07°C, what is the heat of reaction in kJ/mol for this reaction?
a) -10.2 kJ/mol
b) -15.8 kJ/mol
c) -20.6 kJ/mol
d) -25.4 kJ/mol