An instant cold pack is activated by breaking an internal barrier, allowing solid ammonium nitrate to dissolve in water. This dissolution process is represented by the thermochemical equation:
NH4NO3(s)→H2ONH4+(aq)+NO3−(aq)ΔH=+25.7 kJ mol−1 \text{NH}_4\text{NO}_3\text{(s)} \xrightarrow{\text{H}_2\text{O}} \text{NH}_4^+\text{(aq)} + \text{NO}_3^-\text{(aq)} \quad \Delta H = +25.7\text{ kJ mol}^{-1} NH4NO3(s)H2ONH4+(aq)+NO3−(aq)ΔH=+25.7 kJ mol−1Which statement correctly describes the heat energy transfer and the resulting temperature change of the water?
Heat energy is released from the system to the surroundings, causing the temperature of the water to increase because the dissolution is exothermic.
Heat energy is absorbed by the system from the surroundings, causing the temperature of the water to decrease because the enthalpy of the products is greater than that of the reactants.
Heat energy is absorbed by the system from the surroundings, causing the temperature of the water to increase because the enthalpy of the reactants is greater than that of the products.
Heat energy is released from the system to the surroundings, causing the temperature of the water to decrease because the process is endothermic.
