The OH⁻ concentration in an aqueous solution at 25 °C is 7.9 × 10⁻³M, then the concentration of H⁺ ion is 1.28 × 10⁻¹²M.
Concentration of H⁺ will be calculated by using the below equation as:
pH = -log[H⁺]
Or [H⁺] = [tex]10^{-pH}[/tex]
Also we know the realation pH + pOH = 14 and pOH will be calculated as:
pOH = -log[OH⁻]
Given that, [OH⁻] = 7.9 × 10⁻³M
pOH = -log(7.9 × 10⁻³)
pOH = -(-2.102) = 2.102
Putting this value in above realation equation, we get
pH = 14 - 2.102 = 11.89
Now calculating the concentration of H⁺ by using this pH as:
[H⁺] = [tex]10^{-11.89}[/tex]
[H⁺] = 1.28 × 10⁻¹²M
Hence required concentration of [H⁺] is 1.28 × 10⁻¹²M.
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