Statement 1: The magnitude of the lattice enthalpy of NaCl is greater than that of KCl.
Statement 2: Na⁺ is smaller than K⁺, so the magnitude of its hydration enthalpy is larger.

Question

Statement 1: The magnitude of the lattice enthalpy of NaCl is greater than that of KCl. Statement 2: Na + is smaller than K + , so the magnitude of its hydration enthalpy is larger.

TestHub · Accepted Answer

Lattice enthalpy scales inversely with internuclear distance. NaCl has the smaller cation (Na⁺) and, therefore, a shorter internuclear distance and larger lattice enthalpy. Thus, Statement 1 is correct.

The smaller Na⁺ cation also has a larger hydration enthalpy, making Statement 2 correct. However, Statement 1 is explained by the stronger electrostatic attraction within the smaller crystal lattice, not by hydration enthalpy. Therefore, Statement 2 does not explain Statement 1.

The answer is (b).

Chemistry - Thermochemistry Question with Solution | TestHub

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