What is the concentration of Helium in the water?

Question

Helium is dissolved in water with the total pressure of gas (Helium + water vapor) over the water being 2.20 atm. The temperature is 25o C. What is the concentration of Helium in the water?
Give your answer in g/L .
The vapor pressure of water at 25.0oC is 23.8 mm Hg.


Note that kH has units of mol/L -------- mm Hg

Use the law of partial pressures to find vapor pressure of Helium

PLEASE HELP Me!

Answer 1

This is a pretty challenging question. I am sure there must be an equation to predict this concentration (perhaps in a text book or lecture note you posses). I looked up the solubility of Hydrogen in the CRC Handbook of Chemistry and Physics at 0.85 ml/L, but of course this is at STP.

Actually doing some more research I found Henry’s Law.

http://en.wikipedia.org/wiki/Henry%27s_Law

In this page they list the Henry’s K value for Helium at 3.7 x 10-4 mol / (L* ATM).

Converting your vapor pressure 23.8 mm HG * .001316 = 0.0313 ATM

Could your answer be as simple as (3.7 x 10 –4) * (2.20 – .0313) = 0.00080 M/L

Answer 2

ok to do it you take the pressure of He 2.20atm and x by 760 mm Hg to convert = ____ mmHg - 23.8 (vapor press of water). then multiply by henry's constant for He (3.7e-4). take that ans which will be in mol of He/ L and multiply by the molar mass of He (4g) and u will get ur ans in g/L...

the ans should be: 2.439336
Good luck! :)

Answer 3

The answer given above is correct but Kh isn't in ATM but in mmHg so you have to convert from atm to mmHg. Then you have to convert it to grams because thats mol/L and they're asking g/L.