Question

The equation relating approximate barometric pressure (P, in torr) to altitude (h, in m) at room temperature (T, °C) is

ln P = 6.63 – (h/8000)

Diethyl ether, CH₃CH₂OCH₂CH₃, a common organic solvent, has a normal boiling point of 34.6 °C (and thus a vapor pressure of 760 torr at 34.6 °C). At 25 °C, it has a vapor pressure of 532 torr. At what approximate altitude will diethyl ether boil at 25 °C? Where on Earth would it be a problem to keep this solvent liquid?

Answer 1

A liquid boils at a temperature at which its vapor pressure becomes equal to the external (atmospheric pressure at that altitude or barometric pressure) pressure. Given that at 25 °C, the vapor pressure of diethylether is 532 torr, it will boil at an altitude where the atmospheric pressure is also equal to 532 torr i.e., P = 532 in the given equation.

So from the given equation,

Therefore, the diethylether will boil at 25 ° C at an altitude of approximately 2827 metres.

It will be difficult to keep diethylether liquid at a place where elevation from sea level is 2827 metres or above.