Can the equilibrium constant be calculated using both concentration and partial pressure?

[Yixin Angela Wang 2H]

Self-test 11.2A asks for the equation for the equilibrium constant for the reaction between atmospheric oxygen and oxygen dissolved in water. The solution given is K = [O2 ]/PO. Can someone explain to me how this is ok? I thought the entire equation had to be written either in terms of concentration or in terms of partial pressure, but not mixed?

[Victoria Draper 1G]

In order to find the equilibrium constant, the equation does have to be written in terms of concentration or partial pressure but not both. In the answer that is given in the book, I believe they are taking into account Henry's Law which states that the concentration of a solute gas in a solution is directly proportional to the partial pressure of that gas above the solution. This is why the answer is written in that format where it appears to be written in terms of both concentration and partial pressure. Hope this helps!

[Elizabeth Bamishaye 2I]

You are to find one or the other, not both at the same time.

In order to be considered a equilibrium constant of pressure (), it should be a gaseous reaction; p can have units of pressure (e.g., atm or bar).