Question

2. A cold pack consists of an inner pouch containing ammonium nitrate, NHĄNO (), and an outer pouch of water. Twisting the pack breaks the inner pouch and allows the water and ammonium nitrate to mix. As the ammonium nitrate dissolves, the temperature of the surroundings decreases. The energy change per mole of ammonium nitrate dissociated is 25.7 kJ. (a) Classify the reaction as endothermic or exothermic. [ans: endothermic (b) Draw a potential energy diagram for the reaction. Label the change in enthalpy. (c) Write a thermochemical equation for this reaction. H0 NH,NO, (a)] (ans: NH,NO,(s)+25.7 kJ stry

Answer 1

a) the above reaction can very well be classified into an endothermic reaction because it is given very clearly in the question that when the reaction take place the temperature of the surroundings is decreased i.e. the temperature of the system must have increased hence it have gained the heat from the surroundings which is the quality of an endothermic reaction where heat is absorbed.

b) the potential energy diagram for an endothermic reaction is shown in the picture where potential energy of products is greater than that of the reactants.

transition steve AHO ie positive for an endothermic reaction Potential achuared energy energy Ea so Products energy is absorsed Tany change in enthalpy] eacients because P.E. (Pr) > P.E. (R) uachon beaguess-> 1 /

C) the thermochemical equation which is given in the answer is correct as we know it is a endothermic reaction hence the heat is added to the reactant side because we already know that Delta H is positive for endothermic reactions.