# Protons and osmotic potential

In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?

• At the end, both solutions will be equally concentrated in H+, provided the two solutions contains only water and an acidic aqueous solution Apr 8 '20 at 13:35

If the water is pure on both sides, it will have the same pH (assuming the same temperature and pressure). Thus the only way to create a difference in pH would be through the presence of conjugate acids and/or bases other than $$\ce{H_2O}$$, $$\ce{H^+}$$ and $$\ce{OH^-}$$.