Question: how many h30+ molecules are present in 1 liter of water?
Answer: The concentration of pure water is ~55 molar (so there are 55 moles of water in a 1 L bottle -- you can easily calculate this by dividing the mass of 1 L of water by the molar mass of water -- 1000g / 18.03g = 55.46). The concentration of H+ and OH- at pH 7 is 10^-7 molar.