How to find [H3O+] when i have [OH-]?
[H3O^+][OH^-] = Kw = 1E-14
To find the concentration of H3O+ (hydronium ion) when you have the concentration of OH- (hydroxide ion), you can use the concept of the auto-ionization of water.
Water undergoes a self-ionization process in which it produces both H3O+ and OH- ions:
H2O ⇌ H3O+ + OH-
At equilibrium, the product of the concentrations of H3O+ and OH- is constant and can be expressed as the ion product of water, Kw. At room temperature, Kw is approximately 1.0 x 10^-14 (mol/L)^2.
Mathematically, the ion product of water is represented as:
Kw = [H3O+][OH-]
If you know the concentration of OH-, you can rearrange the equation to find the concentration of H3O+:
[H3O+] = Kw / [OH-]
Substituting the value of Kw (1.0 x 10^-14) and the known concentration of OH-, you can calculate the concentration of H3O+.
For example, if the concentration of OH- is 1.0 x 10^-7 mol/L, the calculation would be:
[H3O+] = (1.0 x 10^-14) / (1.0 x 10^-7) = 1.0 x 10^-7 mol/L
Therefore, the concentration of H3O+ would be 1.0 x 10^-7 mol/L in this case.