we have been given the [OH⁻] therefore we can first find the pOH value
pOH scale is used to determine the basicity of a solution
pOH = - log [OH⁻]
pOH = - log (1 x 10⁻¹¹ M)
pOH = 11
after knowing the pOH we can calculate pH using following equation
pH + pOH = 14
since pOH = 11
pH = 14 - 11
pH = 3
pH scale is used to determine how acidic a solution is
once pH is known we can can calculate Hydrogen ion concentration
pH = - log [H⁺]
[H⁺] = antilog (-pH)
[H⁺] = antilog(-3)
[H⁺] = 1 x 10⁻³ M
if pH is less than 7 - solution is acidic
pH = 7 the solution is neutral
pH more than 7 - solution is basic
pH of solution is 3 which is less than 7
therefore solution is acidic
and hydrogen ion concentration is 1 x 10⁻³ M