Question

At 60°c, the ion-product constant of water, kw, is 9.25 × 10–14 . what is the ph of pure water at 60°c ?

Answer 1

Answer:

6.517.

Explanation:

• It is known that for pure water: [H₃O⁺] = [OH⁻], so water is neutral.  

• It also is known that:

Kw = [H₃O⁺][OH⁻] = 9.25 x 10⁻¹⁴.

∵ [H₃O⁺] = [OH⁻].

∴ [H₃O⁺]² = 9.25 x 10⁻¹⁴.

∴ [H₃O⁺] = √(9.25 x 10⁻¹⁴) = 3.041 x 10⁻⁷ M.

∵ pH = - log[H₃O⁺]

∴ pH = - log(3.041 x 10⁻⁷) = 6.517.