(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

We know that for dry air, we have:

-78.08% mol N2 ;

-20.94% mol O2.

This is:

- Y(N2) = 0.7808 for nitrogen (the molar fraction in vapor)

- Y (O2) = 0.2094 for oxygen

Knowing that the Henry's law constants are:

for N2 and O2 are 6.51 x 10^7 Torr and 3.3 x 10^7 Torr, respectively

Calculate the mole fractions of N2 and O2 dissolved in water (xN2 and xO2) under total pressure of 1.000 bar

2. Relevant equations

Henry's law:

The partial pressure = henry's constant k1 x mole fraction of water (x)

P(N2) = K(N2).X(N2)

Same for O2.

Also, from Raoult's law:

Y(N2) = P(N2)/P(tot)

Same for oxygen.

3. The attempt at a solution

I tried applying the equations, but instead of the expected (x(N2)=0.6), I get really small results such as 0.00000651

I am just wondering if I am doing anything wrong by mixing the vapour molar fraction equation with Henry's law for the molar fractions for water?

Thank you.

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# Homework Help: Henry's law: mole fractions

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