3 ms·

Can you explain what hydrogen-heavy means?

• prklmn 11y ago
  The ratio of hydrogen to hydroxide is higher than it normally is. Water naturally dissociates into hydrogen and hydroxide ever so slightly in equal amounts under neutral conditions.
  • logfromblammo 11y ago
    The auto-dissociation constant Kw is 10^-14 mol^2 L^-2. That means that concentration of hydronium [H3O+] ion multiplied by the concentration of hydroxide [OH-] ion is equal to the constant. In pure water, there are no other ions to change the balance, so you get 2 H2O <-> H3O+ + OH-, and each concentration is the square root of the dissociation constant. So 10^-7 mol/L H3O+ and 10^-7 mol/L OH-. The abbreviation "pH" stands for "power hydrogen", and is the negative log10 of the H3O+ concentration. 10^-7 mol/L H3O+ is pH 7, which is neutral. There is also a lesser-known term pOH, which is pretty much pOH + pH = 14 under normal conditions. But that water doesn't stay perfectly neutral for long. CO2 from the atmosphere dissolves into it, using CO2(g) <-> CO2(aq) K_CO2 = 2.0e-3, P_CO2 = 3.6e-4 CO2(aq) + H2O(l) <-> H2CO3(aq) K = 1.3e-3 H2CO3(aq) + H2O(l) <-> H3O+(aq) + HCO3-(aq) Ka1 = 2.0e-4 HCO3-(aq) + H2O(l) <-> H3O+(aq) + CO3--(aq) Ka2 = 4.7e-11 Solving the equilibrium gives you a pH of 5.65 (10^-5.65 mol/L H3O+). Some natural groundwater contains other dissolved minerals, including carbonates (limestone is CaCO3), which pushes the CO2 equilibrium in the other direction, making water more basic (higher pH).