Can someone explain me this question:

Question

What assumption must we make about the dissolving of a gas in water for the solubility evidence to be valid?

what does the question really wants to ask???
I mean is it the observations when the gas dissolves in the liquid or the reason why gas dissolves in a liquid????

Answer 1

We assume the gas does not react with the water to form another compound. O2, N2, He, etc don't react with water when they dissolve (well, perhaps they form hydrates at low low temperatures). CO2 reacts with water to form H2CO3 but the Keq is so small that we usually ignore that. But, for example, HCl gas reacts easily with waterr so the solubility data is not valid for use with Henry's Law.

Answer 2

may you please elaborate more because my teacher did not discuss the Henry's Law yet..

thanks!

Answer 3

Henry's Law simply says that the solubility of a gas in a solvent (usually water) is proportional to the partial pressure of the gas above the liquid. So if a gas dissolves in water at say 25 C to make 0.0001M (that's 0.0001 mols gas/L soln) at 1 atm pressure for the gas, then it will be 0.0002M at 2 atm pressure and 0.0003M at 3 atm etc. That always assumes that the gas does not react with the water. But HCl gas is very very soluble in water (about 37% HCl in a saturated solution or about 11 M) so none of this applies.

Answer 4

Oh ok.. thanks:)