Calculate the pH of a solution at 25.0 °C that contains 1.94 × 10-10 M hydronium ions.

Calculate the pH of a solution at 25.0 °C that contains 1.94 × 10-10 M hydronium ions.

First convert 1.94E-10 to pOH.

Therefor, pOH = -log(OH^-)

Then,

pH + pOH = pKw = 14

We know that pOH and pKw, solve for pH.