Question

Liquid A has a normal boiling point of 64 deg C and liquid B has a normal boiling point of 98 deg C. a) which has the greater vapor pressure? b) which has the weaker intermolecular attractive forces in the liquid state?

Answer 1

a)

we know that

vapor pressure and boiling point are inversely proportional

so

higher the boiling point , lower the vapor pressure

and

lower the boiling point , higher the vapor pressure

given

boiling point of A = 64

boiling point of B = 98

boiling point of A < boiling point of B

so

vapor pressure of A > vapor pressure of B

so

A has greater vapor pressure

b)   we know that

intermolecular forces and boiling point are directly proportional

so

higher the intermolecular forces , higher the boiling point

this is because

it is tough to break the forces between then and cover to gas state

now

lower the intermolecular forces , lower the boiling point

because

the atoms can easily be separated and converted into gas state

now

boiling point of A < boiling point of B

so

intermolecular forces of A < intermolecular forces of B

so

A has the weaker intermolecular attractive forces