Question

In a gaseous mixture of a `2.0*L` volume, at `755*"mm Hg"`, and a temperature of `346*K`, `P_"dinitrogen"=355*mm*Hg`. What are the molar quantities of helium and dinitrogen?

Answer 1

`"Dalton's Law of Partial Pressures tells us that........."`, I get approx. `150*mg` of helium............

Explanation:

`"In a gaseous mixture, the pressure exerted by a component gas"`
`"is the same as the pressure if it ALONE occupied the container."`

`"The total pressure is the sum of the individual partial pressures."`

And this `P_"mixture"=P_"He"+P_("N"_2)`

And so `P_"He"=(755-355)*mm*Hg=400*mm*Hg`.

Given that we now `P_"He"` we can calculate its equivalent mass by means of the Ideal Gas Equation.......

`n=(PV)/(RT)=((400*mm*Hg)/(760*mm*Hg*atm^-1)xx2.0*L)/(0.0821*(L*atm)/(K*mol)xx346*K)=0.0371*mol`.

Which represents a mass of `0.0371*molxx4.0*g*mol^-1` with respect to helium gas.