Which of the following should have the largest Henry's law constant (kh) in water?

Ar
CO2
CO
CH3CH3
Xe

4 answers

I would think CO2 because CO2 reacts with water to form H2CO3 and the corresponding ions, HCO3^- and CO3^-2 and H^+.
CO2 + H2O ==> H2CO3 ==>H^+ + HCO3^-
HCO3^- ==> H^+ + CO3^-2.
I look up the molarity of CO2, CO, and Ar and CO2 was the highest. The other two weren't listed.
actually that is wrong. i put that as my answer choice as first too.
The answer is CO
how can I find the solubility of a gas?