Suppose we have a source of O$_2$ bubble formation in water at specific nucleation sites, how can we estimate the water vapour pressure inside the O$_2$ bubbles?
I know that:
(1): $p_\mathrm{O_2}+p_\mathrm{H_2O} = p_\mathrm{tot}$
(2): $c_\mathrm{O_2} = K_\mathrm{O_2}\cdot p_\mathrm{O_2}$ (Henry's law)
where $c_\mathrm{O_2}$ is the concentration of $O_2$ in the liquid phase, and $p_x$ are partial pressures. How can I get $p_\mathrm{H_2O}$ probably as a function of $O_2$ gas pressure?