The density of a mixturee of `O_(2) and N_(2)` gases at 1 atm and 273 K is 0.0013 gm/mL. If partial pressure of `O_(2)` in the mixture is A, then calculate value of 25 A.

Answer

`0.28 atm`

Explanation

Let `n_(1) " and " n_(2)` moles of `N_(2) " and " O_(2)` be present in the mixture respectively.
Average molecular mass of the mixture `= (28 n_(1) + 32 n_(2))/(n_(1) + n_(2))`...(i)
Average molecular mass from general gas equation,
`M = (D)/(P) xx RT = (1.3)/(1) xx 0.0821 xx 273 = 29.137`....(ii)
So, `(28 n_(1) + 32 n_(2))/(n_(1) + n_(2)) = 29.137 " or " (4n_(2))/(n_(1) + n_(2)) = 1.137`
or `(n_(2))/(n_(1) + n_(2)) = 0.28 =` mole fraction of oxygen
Partial pressure of `O_(2) = 0.28 xx 1 = 0.28 atm`