Question

What is the final temperature in a squeezed hot pack that contains 27.6 g of LiCl dissolved in 102 mL of water?

Assume a specific heat of 4.18 J/(g⋅∘C) for the solution, an initial temperature of 25.0 ∘C, and no heat transfer between the hot pack and the environment.

Instant hot packs contain a solid and a pouch of water. When the pack is squeezed, the pouch breaks and the solid dissolves, increasing the temperature because of the exothermic reaction. The following reaction is used to make a hot pack: LiCl(s)⟶Li+(aq)+Cl−(aq)ΔH=−36.9kJ