Question

The salt potassium hydroxide dissolves in water according to the reaction:

• KOH(s) K⁺(aq) + OH^-(aq)

(a) Calculate the standard enthalpy change ΔH° for this reaction, using the following data:

• KOH(s) = -424.8 kJ mol^-1
  K⁺(aq) = -252.4 kJ mol^-1
  OH^-(aq) = -230.0 kJ mol^-1

  kJ

(b) Calculate the temperature reached by the solution formed when 8.05 g of KOH is dissolved in 0.162 L of water at 21.8 °C. Approximate the heat capacity of the solution by the heat capacity of 162 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?

Hot or cold pack

Answer 1

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