Given below is the tabular column of ionic compound and lattice energy arranged randomly.
From the above table, what may be the correct value of Lattice energy for KCl.

Question

Given below is the tabular column of ionic compound and lattice energy arranged randomly. From the above table, what may be the correct value of Lattice energy for KCl.

TestHub · Accepted Answer

Question Explanation: Find the lattice energy of KCl from the given data.

Concept: Lattice energy is proportional to the charge of ions divided by the sum of ionic radii.

$L a tt i ce E n er g y \propto \frac{C ha r g e o f I o n s}{S u m o f I o ni c R a d ii}$

Solution:

• Lattice energy decreases down the group as cation size increases.

• Given: NaCl has a lattice energy of approximately $787 k J / m o l$ , which is closest to $701 k J / m o l$ .

• MgCl₂ and BaCl₂ have higher charges, resulting in larger lattice energies ( $2326 k J / m o l$ and $2033 k J / m o l$ , respectively). These values are assigned to MgCl₂ and BaCl₂.

• KCl has a larger cation (K⁺) than Na⁺, so its lattice energy will be slightly less than that of NaCl, approximately $769 k J / m o l$ .

Final Answer: $701 k J / m o l$

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