Thiophene, C₄H₄S, is a fairly volatile liquid with a vapor pressure of 40.0 torr at 12.5 $\degree$C, and its normal boiling point is 84.0 $\degree$C.Calculate an estimate of thiophene's enthalpy of vaporization in kJ/mol.

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The Clausius-Clapeyron equation can be used to estimate the enthalpy of vaporization ($\Delta H_{vap}$) from the vapor pressure at two temperatures. The equation in its linear form is:$$\ln\left(\frac{P_2}{P_1}\right) = -\frac{\Delta H_{vap}}{R}\left(\frac{1}{T_2} - \frac{1}{T_1}\right)$$Given:- $P_1 = 40.0$ torr at $T_1 = 12.5^\circ C = 285.65 K$- $P_2 = 760.0$ torr (normal boiling point pressure) at $T_2 = 84.0^\circ C = 357.15 K$- $R = 8.314$ J/mol·K (universal gas constant)First, convert pressures to the same units (torr to atm, if necessary, or just use torr since the units will cancel out):$$\ln\left(\frac{760}{40}\right) = -\frac{\Delta H_{vap}}{8.314}\left(\frac{1}{357.15} - \frac{1}{285.65}\right)$$Solving for $\Delta H_{vap}$ gives a positive value, indicating endothermic process (energy is absorbed to vaporize the liquid), which matches choice (B) when calculated correctly.

Thiophene, C4H4S, Is a Fairly Volatile Liquid with a Vapor °\degree°

Thiophene, C₄H₄S, Is a Fairly Volatile Liquid with a Vapor $\degree$