The normal boiling point of mercury (Hg) is 356.7 °C. What is the vapor pressure of mercury at 322 °C? (∆Hvap = 58.51 kJ/mol)

The vapor pressure of mercury at 322°C is 0.521 atm

Explanation:

To calculate the final pressure, we use the Clausius-Clayperon equation, which is:

where,

= initial pressure which is the pressure at normal boiling point = 1 atm

= final pressure which is vapor pressure of mercury = ?

= Enthalpy of vaporization = 58.51 kJ/mol = 58510 J/mol     (Conversion factor: 1 kJ = 1000 J)

R = Gas constant = 8.314 J/mol K

= initial temperature which is normal boiling point =

= final temperature =

Putting values in above equation, we get:

Hence, the vapor pressure of mercury at 322°C is 0.521 atm