Liquid a has a vapor pressure of 264 torr at 20∘c, and liquid b has a vapor pressure of 96.5 torr at the same temperature. if 5.50 moles of liquid a and 8.50 moles of liquid b are combined to form an ideal solution, what is the total vapor pressure (in torr) above the solution at 20.0∘c?

161.8 torr

Explanation:

According to Raoult's law, the vapor pressure of a component at a given temperature is equal to the mole fraction of that component multiplied by the vapor pressure of that component in the pure state.

and

where, x = mole fraction

= pressure in the pure state

According to Dalton's law, the total pressure is the sum of individual pressures.

,

,

The total vapor pressure above the solution is 161.8 torr.