Question

How does PCl5 exist in its solid state?

(a) [PCl4]^+[PCl6]^–

(b) [PCl3]^2+[PCl7]^2-

(c) [PCl2]^3+[PCl8]^3-

(d) [PCl5][PCl5]

This question was addressed to me in an internship interview.

Asked question is from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12

Answer 1

Right choice is (a) [PCl4]^+[PCl6]^–

For explanation I would say: Phosphorus pentachloride is a pale yellow crystalline solid with a characteristic pungent smell. In the solid state, it exists as an ionic solid, [PCl4]^+[PCl6]^– in which the cation, [PCl4]^+ is tetrahedral while the anion, [PCl6]^– is octahedral.