Question

Perry’s Handbook (7^thed.) lists the heat of solution for aluminum chloride (AlCl₃) in water as -77.9 (kcal/mole AlCl₃) for a dilution of 600 moles of water for 1 g of AlCl₃at 18°C (reference state is pure solvent and solute at 18°C). If this solution (600 moles water, 1 g AlCl₃, both initially at 18°C when pure) was prepared, how much heat must be added/removed (specify which) to keep the temperature at 18°C? Why do you have to heat/cool the solution to keep the temperature at 18°C, when both pure chemicals are already at 18°C? *Note: Heats of solution in Perry’s are given as the negative heat of solution without explanation. I have switched the sign from Perry’s to give the true heat of solution. If you have doubts, compare the heat of solution of NaOH in water from Perry’s and our text.

Answer 1