pH= 10,55.
The equation for calculation of pH from pOH is pH + pOH = 14. So pH = 14 – 3,45. pH represent a negative logarithm with base 10 of concentration of H⁺ ion, pH = -log[H⁺], and pOH represent negative logarithm with base 10 of concentration of OH⁺ ion. In clean neutral water at 25°C the concentration of H⁺ and OH⁻ is [H⁺] x [OH⁻] = 10⁻¹⁴ mol/dm³ and it is called the ionic product for water (Kw)