Question

The electron gain enthalpy of chlorine is $3.7eV$. How much energy in kcal is released when $2g$ of chlorine is completely converted to ${Cl}^{-}$ ions in the gaseous state?
($1eV=23.06kcal$)

• A. $5.8kcal$
• B. $3.52kcal$
• C. $4.8kcal$
• D. None of these

Answer 1

Answer: (C)

$4.8kcal$

Electron affinity in $eV=3.7$

Electron affinity in $kcal/mol=3.7\times 23.06=85.322$ $kcal/mol$

No.of moles $=\frac{2}{35.5}=0.056338$

$1$ $mole$ gives $85.322$ $kcal$

$0.056338$ gives $85.322\times 0.056338=4.806$ $kcal$