Question

The enthalpy of vaporisation of a substance is $8400J{mol}^{-1}$ and its boiling point is $-{173.15}^{\circ }C$. The entropy change for vaporisation is:

Answer 1

Correct Answer: 84

Explanation:
Given: Enthalpy of vaporisation of a substance is: $8400J{mol}^{-1}$Temperature or boiling point of substance is: $-{173.15}^{\circ }C$ We have temperature in Kelvin,$=$ Celsius temperature $+$${273.15}^{\circ }C$$=-{173.15}^{\circ }C+{273.15}^{\circ }C$$=100K$Now, we know,Change in entropy, $\mathrm{\Delta }S=\frac{q_{r}ev}{T}$$=\left(\frac{8400}{100}\right)$$=84Jmo{l}^{-1}{K}^{-1}$ Hence, the correct answer is '84'.