[spirit]

I'm having difficulty solving the following problem:

Butane (C4H10) molar enthalpy of vaporization is 22.44 kJ/mol and its normal boiling point is –0.40 °C. A 250-mL sealed Erlenmeyer flask contains 0.55 g of butane at –22 °C.

a. What is the equilibrium vapor pressure under these conditions?
b. How much butane is present as a liquid under these conditions?
c. If the butane in the sealed flask is heated to 25 °C, how much of the butane remains in the liquid state?

Please *delete me*