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)

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 $LiCl=-408.8kJmo{l}^{-1}$
$\Delta H_f$ for $NaCl=-412.5kJmo{l}^{-1}$
$\Delta H_f$ for $CsCl=-433kJmo{l}^{-1}$
$\Delta H_f$ for $KCl=-436kJmo{l}^{-1}$