Two crystalline solids, CaS and CaCl₂

CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding

Problem

Two crystalline solids, CaS and CaCl₂, are compared. Which compound is expected to have the higher melting point, and why? (a)

\text{CaCl}_2

, primarily because having two chloride ions per calcium ion produces twice as many attractive interactions in the lattice (b)

\text{CaS}

, primarily because the product of ionic charges is larger than in

\text{CaCl}_2

(c)

\text{CaCl}_2

, primarily because the

\text{Cl}^-

ion is smaller, shortening the distance between ion centers (d)

\text{CaS}

, primarily because the highly polarizable

\text{S}^{2-}

ion creates stronger attractions with

\text{Ca}^{2+}