Given that the boiling points of ethanol and diethyl ether are 78.1°c and 34.6°c, respectively, which should have the higher vapor pressure at 20.0°c?

- Diethyl ether would have higher vapor pressure at 20.0 degree C.

Explanations:- Boiling point is the temperature at which the vapor pressure equals to the atmospheric pressure.

Looking at the given vapor pressure values, ethanol needs to be heat up at 78.1 degree C to makes it's vapor pressure equals to atmospheric pressure where as diethyl ether only needs to be heat up at 34.6 degree C.

Hence, lower is the boiling point, higher is the vapor pressure.

Now, 20.0 degree C is more closer to 34.6 degree C . it means the temperature difference is less for diethyl ether as compared to ethanol.

So, as the boiling point of diethyl ether is low, the vapor pressure of it would be higher at 20.0 degree C.