Question

The stability of the following alkali metal chlorides follows the order

• A. LiCl > KCl > NaCl > CsCl
• B. CsCl > KCl > NaCl > LiCl
• C. NaCl > KCl > LiCl > CsCl
• D. KC1 > CsCl > NaCl > LiCl

Answer 1

Answer: (D)

KC1 > CsCl > NaCl > LiCl

Answer 2

Stability of compound depends upon its enthalpy of formation $\Delta H _{ f }$. The more negative value of $\Delta H _{ f }$ shows more stability of a compound. Thus, $KCl$ is more stable and $LiCl$ is least stable. $\Delta H _{ f }$ for $LiCl =-408.8\, kJ\, mol ^{-1}$ $\Delta H _{ f }$ for $NaCl =-412.5\, kJ\, mol ^{-1}$ $\Delta H _{ f }$ for $CsCl =-433\, kJ\, mol ^{-1}$ $\Delta H _{ f }$ for $KCl =-436\, kJ\,mol ^{-1}$