Question

What are the partial pressures of the gases?

Answer 1

In a gaseous mixture, the partial pressure exerted by a component gas is the same as the pressure it would exert if it alone occupied the container.

Explanation:

The total pressure is the sum of the individual partial pressures:

And thus `P_"total"=P_1+P_2+.........P_n`

Assuming ideality,

`(n_"total"RT)/V=(n_1RT)/V+(n_2RT)/V+.........(n_nRT)/V`

`(n_"total"RT)/V=(RT)/V{n_1+n_2..........+n_n}`

And thus the partial pressure of any component gas is proportional to the mole fraction, the constant of proportionality `=` `(RT)/V`.

Clearly, this law assumes a mixture of non-reacting gases. And thus now we breathe dioxygen gas at a pressure of approx. `0.20*atm`.