Consider an equilibrium reaction with an aqueous solution $\ce{A(aq)}$ in equilibrium phase with gas: $$\ce{A(aq) + B(g) <=>[$K_\mathrm{eq}$] C(g)}$$ Would the equilibrium constant have aqueous solution $\ce{A(aq)}$ contributing to it?
In my opinion I think it would. Can anyone please correct me? Also, please help me find literature which explains equilibrium constant in details.