# Worksheet: The Clausius–Clapeyron Equation

In this worksheet, we will practice using the Clausius–Clapeyron equation to convert between changes in temperature and vapor pressure.

**Q1: **

Under 101.3 kPa of atmospheric pressure, the boiling point of acetone is and the enthalpy of vaporization is 31.3 kJ/mol. Estimate the vapor pressure of acetone at .

**Q2: **

The vapor pressure of isooctane is 10.0 kPa at and 100.0 kPa at . Estimate the enthalpy of vaporization of isooctane.

**Q3: **

The vapor pressure of ethanol is 5.95 kPa at and 75.0 kPa at . Estimate the enthalpy of vaporization of ethanol.

**Q4: **

When the temperature of a liquid is increased, the vapor pressure increases from to . How does the ratio vary with the enthalpy of vaporization?

- ALinearly
- BLogarithmically
- CInversely
- DExponentially
- EQuadratically

**Q5: **

For a compound X, which enthalpy change is associated with the process ?

- AEnthalpy of vaporization
- BEnthalpy of fusion
- CLattice enthalpy
- DEnthalpy of sublimation
- EEnthalpy of formation

**Q6: **

The normal boiling point of is 331.9 K, and its vapor pressure at 298 K is 0.287 bar. Within the approximations inherent to the Clausius-Clapeyron equation, what value of (the molar enthalpy of vaporization) for would be compatible with this data?

- A 70.6 kJ/mol
- B kJ/mol
- C kJ/mol
- D 33.2 kJ/mol

**Q7: **

At , the vapor pressure of chloroform is 22.4 kPa and the enthalpy of vaporization is 31.40 kJ/mol. Estimate the boiling point of chloroform under 1 bar of atmospheric pressure.

**Q8: **

Under 1.00 bar of atmospheric pressure, the boiling point of furan is and the enthalpy of vaporization is 27.71 kJ/mol. Estimate to 3 significant figures the vapor pressure of furan at .

- A 55.6 kPa
- B 78.6 kPa
- C 22.9 kPa
- D 43.7 kPa
- E 32.1 kPa

**Q9: **

Under 1.000 bar of atmospheric pressure, the boiling point of nitromethane is . The vapor pressure at is 15.48 kPa. Estimate to 3 significant figures the enthalpy of vaporization of nitromethane.

**Q10: **

Which of the following statements is incorrect?

- AThe maximum number of phases that can coexist in a system composed of four components is equal to six.
- BIt is impossible for four phases of a single pure substance to coexist at equilibrium.
- CTwo phases at equilibrium must have the same pressure.
- DThe Clausius-Clapeyron equation can be used in the characterization of solid-liquid phase equilibria.