Question

The entropy of vaporization of benzene is $85J{K}^{-1}mo{l}^{-1}.$ When $117g$ benzene vapourization:

• A. $-85J{K}^{-1}$
• B. $-85\times 1.5J{K}^{-1}$
• C. $85\times 1.5J{K}^{-1}$
• D. none of these

Answer 1

The correct option is D none of these

Number of moles of benzene =$\frac{Givenmass}{Molarmass}=\frac{117}{78}=1.5moles$

$\Delta S=No.Ofmolesofbenzene\times {\Delta }_{vap}S$

$\Rightarrow \Delta S=1.5\times 85=127.5J/K$

We know that $\Delta S_{system}=-{\Delta }_{surrounding}S$

$\Rightarrow {\Delta }_{surrounding}S=-127.5J/K$

Hence, the correct option is D.