Question

The salt ammonium chloride dissolves in water according to the reaction:
NH4Cl(s) NH4+(aq) + Cl-(aq)

(a) Calculate the standard enthalpy change ΔH° for this reaction, using the following data:
NH4Cl(s) = -314.4 kJ mol-1
NH4+(aq) = -132.5 kJ mol-1
Cl-(aq) = -167.2 kJ mol-1

kJ

(b) Calculate the temperature reached by the solution formed when 35.3 g of NH4Cl is dissolved in 0.160 L of water at 24.6 °C. Approximate the heat capacity of the solution by the heat capacity of 160 g of pure water (specific heat capacity = 4.18 J g-1 °C-1), ignoring the mass of the salt.

°C

(c) Heats of reaction find practical application in hot packs or cold packs. Would this dissolution reaction be appropriate for the preparation of a hot pack or a cold pack?

Answer 1

(b) mcAT 9 14.2X1o 160 es fere wah C 18 3 ATE T 3 147Xlo-160x 41X CT-24 6 T-46. 5C Teuskraline nctave 46.5C Yes this diolulin peck ice the teukeralur eeaue ter NCe alt ialntin diifiaut re is efective as a het and can be wl as a st pack

hreatn AHseselauls MAtucts Acc. to reacln N4 NH4CS) AH AH NH CL antA 13.5-167.)-314.4) -299 9 t 3/9.4 kJnist Aatin14. kJ/nuel