The hydroxide ion concentration, [OH-] = 2.439 x 10⁻¹⁰
Equilibrium of water and the ions :
[tex]\tt 2H_2O(l)\rightarrow H_3O^+(aq)+OH^-(aq)[/tex]
[tex]\tt Kc=\dfrac{[H_3O^+][OH^-]}{H_2O}[/tex]
Kc[H₂O] is the ion equilibrium constant for water ⇒ Kw.
The product of the concentrations of these ions (H₃O⁺ and OH⁻)at equilibrium at 25°C is 1.0 x 10⁻¹⁴ M
[H₃O⁺] [OH⁻] = 1.0 x 10⁻¹⁴ M = Kw
The hydrogen ion concentration of [H⁺]=4.1 x 10⁻⁵ M, so the hydroxide ion concentration, [OH-] :
[tex]\tt 4.1\times 10^{-5}\times [OH^-]=1.10^{-14}\\\\(OH^-]=\dfrac{1.10^{-14}}{4.1\times 10^{-5}}\\\\(OH^-]=2.439\times 10^{-10}[/tex]
