A student investigates the heat released when solid potassium hydroxide is dissolved in water. In a coffee-cup calorimeter, 10.0 g of KOH pellets are quickly added to 100.0 g of water at 22.5 °C. The maximum temperature recorded is 37.8 °C. Assume that (i) no heat is lost to the surroundings, (ii) the specific heat capacity of the solution is 4.18J g−1∘C−1, and (iii) the density of the solution remains 1.00g mL−1.
(a) Calculate the quantity of heat q absorbed by the solution.
(b) Determine the molar enthalpy of dissolution of KOH at 22.5 °C, clearly indicating its sign.
(c) Explain, at the particulate level, why the dissolution of KOH is exothermic, referring explicitly to the relative strengths of interactions broken and formed.
(d) The student proposes doubling the mass of KOH while keeping the volume of water the same to create a compact hand warmer. Predict qualitatively how the final temperature change would deviate from doubling and justify your reasoning, considering both thermodynamic and practical factors.