Problem: A gaseous mixture of O2 and Kr has a density of 1.181 g/L at 485 torr and 300. K. What is the mole percent O2 in the mixture?
Attempt: I have tried everything possible that I know and I can't get anywhere close to the solution. d=m/v=pM/RT... nothing works. Help please?
Mole fraction help
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Sam
- Staff Member
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You need to find an average molar mass of the mixture.
If the fraction of O2 in the mixture is x then for Kr it is 1-x.
The average molar mass is: M[O2] x + M[Kr] (1-x)
Now you can express then density in terms of this average molar mass:
(M[O2] x + M[Kr] (1-x) ) P /(RT) = d
From the equation above you van find x.
And multiplying it by 100% will give you the answer!
Sam
If the fraction of O2 in the mixture is x then for Kr it is 1-x.
The average molar mass is: M[O2] x + M[Kr] (1-x)
Now you can express then density in terms of this average molar mass:
(M[O2] x + M[Kr] (1-x) ) P /(RT) = d
From the equation above you van find x.
And multiplying it by 100% will give you the answer!
Sam