IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry - Please explain-not understanding

Himanshu346

The partial pressure of ethane over a solution containg 6.56 x 10^-3 g of ethane is 1 bar.If the solution contains 5.00 x 10^-2g of ethane, then what

shall be the partial pressure of the gas?

tarinbansal

Simply apply Henry's law.

P = K x^o

where x^o = mole fraction of the gas in the solution.

So, P₁ = K x^o₁

P₂ = K x^o₂

Therefore, P₁/P₂ = x^o₁/ x^o₂

Hence, find P₂.

Himanshu346

But from where we will find X⁰1 and X⁰2

tarinbansal

U know the mass of ethane in each case and also the molar mass of ethane. SO u know the no. of moles of ethane in each case.

Now, mole fraction= moles of ethane/total no of moles
Let the moles of ethane=n, and moles of solvent=N.
As the mass of ethane taken is very less, we can assume n+N~N.
Now while calculating the ratio, this N will get cancelled and U will get ur answer.

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