A disposable cold pack contains solid separated from water
CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics
Problem
A disposable cold pack contains solid NH4NO3 separated from water. When the barrier is broken, the salt dissolves and the pack feels cold to the touch. Which of the following best explains this temperature change?
(a) The dissolution is endothermic because heat flows from the system to the surroundings, cooling the water.
(b) The dissolution is exothermic because lattice energy is released into the surroundings as heat.
(c) The dissolution is endothermic because the system absorbs heat from the surroundings, lowering the pack’s temperature.
(d) The dissolution is exothermic because the increase in entropy drives heat out of the solution.