Question

Which would you expect to have the highest vapor pressure at room temperature?

CH2H5OH

CH3OH

C3H7OH

Answer 1

The vapor pressure of a liquid is the equilibrium pressure of a vapour above its liquid in a closed system. Different factors which are affecting vapour pressure are: types of molecules and temperature. If the intermolecular forces between molecules are relatively strong, the vapour pressure will be low and boiling point will be high. If intermolecular forces are relatively weak, the vapour pressure will be high and boiling point will be low. At a higher temperature, vapour pressure would be high. As the boiling point of methanol is less its vapour pressure will be high.

Methanol (CH3OH) 64.7 °C

Ethanol (C2H5OH) 78.37 °C

Propanol (C3H7OH) 97 °C