Final answer:
The salt that will have the maximum cooling effect when 0.5 mole of the salt is dissolved in the same amount of water is HBr (Hydrobromic acid), with an enthalpy of solution (ΔHsoln) of 83.3 J/mol, as it absorbs the most heat from its surroundings during dissolution.
Therefore the correct answer is option c. HBr (∆=83.3 J mol⁻¹)
Step-by-step explanation:
The student is asking about the cooling effect of salts when they dissolve in water, which is related to the enthalpy of solution for each salt. The enhtalpy of solution, often represented as ΔHsoln, indicates whether heat is absorbed (endothermic) or released (exothermic) when a solute dissolves in a solvent. An endothermic process should result in a cooling effect since heat is absorbed from the surroundings. To find the salt with the maximum cooling effect, we should look for the one with the highest positive integral enthalpy of solution.
Given the integral heats of solution at 298 K for the salts:
- KNO₃ (Δ=35.4 J mol⁻¹) - endothermic, potential cooling effect
- NaCL (Δ=5.35 J mol⁻¹) - endothermic, but lower in magnitude
- HBr (Δ=83.3 J mol⁻¹) - this has the highest positive value, indicative of a strong endothermic process and therefore the greatest cooling effect
- KOH (Δ=55.6 J mol⁻¹) - also endothermic, but not as high as HBr
Therefore, the salt that will have the maximum cooling effect when dissolved in water is HBr, with an enthalpy of solution of 83.3 J mol⁻¹.