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Consider the given data: (a) HCl(g) + 10 H2O(l) → HCl.10 H2O ΔH = −69.01 kJ mol−1 (b) HCl(g) + 40 H2O(l) → HCl.40 H2O ΔH = −72.79 kJ mol−1 Choose the correct statement: (1) Dissolution of gas in water is an endothermic process. (2) The heat of solution depends on the amount of solvent. (3) The heat of formation of HCl solution is represented by both (a) and (b). (4) The heat of dilution for the HCl (HCl.10 H2O to HCl.40 H2O) is 3.78 kJ mol−1.

1. Dissolution of gas in water is an endothermic process.
2. The heat of solution depends on the amount of solvent.
3. The heat of formation of HCl solution is represented by both (a) and (b).
4. The heat of dilution for the HCl (HCl.10 H2O to HCl.40 H2O) is 3.78 kJ mol−1.

Correct answer: The heat of dilution for the HCl (HCl.10 H2O to HCl.40 H2O) is 3.78 kJ mol−1.

Solution

The heat of dilution is calculated by taking the difference in enthalpy changes between the two dissolution processes, which shows that the energy change when diluting HCl from a more concentrated solution to a more dilute one is indeed 3.78 kJ mol−1.

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