Question 11.2.4: Determine enthalpy of vaporization graphically using the Cla......
Determine enthalpy of vaporization graphically using the Clausius–Clapeyron equation.
The vapor pressure of sulfur dioxide has been measured over a range of temperatures.Use these data to calculate ΔH_{\text{vap}} for SO_{2}.
| T(K) | P(mm Hg) |
| 220 | 81.6 |
| 230 | 147.4 |
| 240 | 253.6 |
| 250 | 417.7 |
You are asked to calculate the enthalpy of vaporization for a liquid.
You are given the vapor pressure of the liquid at different temperatures.
Use the general form of the Clausius–Clapeyron equation and a plot of ln P versus 1/T to determine ΔH_{\text{vap}}
According to Equation 11.1, the slope of this linear plot is equal to -ΔH_{\text{vap}}/R.
ln P = \frac{-\Delta H_{\text{vap}}}{RT} + C (11.1)
slope = \frac{-\Delta H_{\text{vap}}}{R}
-2993.8 k^{-1} = \frac{-\Delta H_{\text{vap}}}{8.3145 \times 10^{-3} \text{ kJ/mol} \cdot \text{K}}
ΔH_{\text{vap}} 24.9 kJ/mol
