By the chemical system of ammonium nitrate
qrxn = - (qwater + qcalorimeter).
The heat lost by the calorimeter water, qwater, depends on the specific heat of water, Csp and ΔT, while the heat lost by the calorimeter, qcalorimeter, depends on the heat capacity, cp and ΔT.
Temperature initial 9.8 degrees celcius
Temperature final 21.5 degrees celcius
Mass water 25.086 Grams.
Mass of ammonium nitrate(salt) 5.109 Grams.