Apentix/AP Chemistry/Unit 3: Intermolecular Forces and Properties/Question
AP Chemistryeasymcq1 pt

Solid KCl does not conduct electricity, but molten KCl conducts well. Which statement explains the difference?

A.Melting frees the ions from fixed lattice positions so they can migrate and carry charge
B.Covalent bonds inside KCl break on melting and release free electrons
C.Solid KCl contains no charged particles until it melts
D.Molten potassium transfers extra electrons to chlorine, generating current

Explanation

Core Concept

Conductivity requires mobile charged particles. Solid KCl already contains K+ and Cl- ions, but strong electrostatic attractions pin each one to its lattice site, so no charge can flow toward an electrode. Melting destroys the rigid lattice while leaving the ions intact, and the freed ions drift under an applied voltage. Only mobility changes between the two phases, not the identity of the charge carriers.

Correct Answer

AMelting frees the ions from fixed lattice positions so they can migrate and carry charge

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