Question

What is partial pressure of oxygen at sea level?

Answer 1

`P_(O_2)=0.21xx1*atm`

Explanation:

This illustrates old Dalton's Law of Partial Pressures. In a gaseous mixture, the partial pressure exerted by a component gas is the same as if it alone occupied the container.....

`P_"Total"=SigmaP_"component gases"`

`=P_1+P_2.....+P_n`, assuming ideality.....

`P_"Total"=(n_1RT)/V+............(n_nRT)/V`

`P_"Total"=(RT)/V{n_1+n_2+....n_n}`

And thus `P_1/P_"Total"=((RT)/Vn_1)/((RT)/V{n_1+n_2+....n_n})`

`P_1/P_"Total"=(n_1)/({n_1+n_2+....n_n})=chi_(n_1)`

Where `chi_(n_1)="mole fraction of the component "`

And here the container is conveniently the atmosphere, which to a first approx. is `78%` dinitrogen, and `21%` dioxygen......

And so what is `P_(O_2)`?