Question

A mixture of helium and neon gases is collected over water at 28.0°C and 745 mmHg. If the partial pressure of helium is 368 mmHg, what is the partial pressure of neon?

Answer 1

`P_"Total"` `=` `P_"He"+P_"Ne"+P_"SVP"`

Explanation:

The partial pressures are additive; but to solve the problem we need 1 more parameter, `P_"SVP"`, the `"saturated vapour pressure"`, which is the `"vapour pressure"` of water at the given temperature. `P_"SVP"=18*mm*Hg` at `301*K`.

From above, `P_"Ne"=P_"Total"-P_"He"-P_"SVP"`

`=(745-368-18)*mm*Hg` `=` `??*mm*Hg`.