Final answer:
The concentration of H3O+ ion, when the [OH-] is 1x10^-13 M, is calculated using the ion-product constant for water (Kw = 1.0 × 10^-14 M2) and is found to be 1.0 x 10^-1 mol/L.
Step-by-step explanation:
To find the concentration of H3O+ ion when you know the concentration of OH- ion ([OH-] = 1x10^-13 M), you use the ion-product constant for water (Kw), which at 25°C is 1.0 × 10^-14.
The formula that relates the concentration of hydronium ions ([H3O+]) and hydroxide ions ([OH-]) in an aqueous solution is Kw = [H3O+][OH-].
Substituting the known [OH-] into the equation gives us Kw = [H3O+] × 1x10^-13. To solve for [H3O+], divide both sides of the equation by the concentration of [OH-], which gives us [H3O+] = Kw / [OH-].
Inserting the values yields [H3O+] = (1.0 × 10^-14) / (1x10^-13) = 1.0 x 10^-1 M.
Therefore, the concentration of H3O+ ion is 1.0 x 10^-1 mol/L.