Thermochemistry

 50) m_w = 60.0 g H₂O          T_i = 23.0°C          m = 3.88 g NH₄NO₃

       c_w = 4.18 J/g•K             T_f = 18.4°C

       NH₄NO₃(s) NH₄⁺(aq) + NO₃^-(aq)

      q_l = mc_wΔT

      q_l = 63.88 g x 4.18 J/g•K x (23.0°C - 18.4°C) = 1.2 x 10³ J

      ΔH = q/n = 1.2 x 10³ J/3.88 g NH₄NO₃ x 1 kJ/10³ J x 80.06 g NH₄NO₃/1 mol NH₄NO₃ = 25 kJ/mol NH₄NO₃