Answer : The vapor pressure of propane at
is 17.73 atm.
Explanation :
The Clausius- Clapeyron equation is :

where,
= vapor pressure of propane at
= ?
= vapor pressure of propane at normal boiling point = 1 atm
= temperature of propane = 
= normal boiling point of propane = 
= heat of vaporization = 24.54 kJ/mole = 24540 J/mole
R = universal constant = 8.314 J/K.mole
Now put all the given values in the above formula, we get:


Hence, the vapor pressure of propane at
is 17.73 atm.