How does dilution affect the pH of a basic solution?
The pH of a basic solution is greater than 7.
As you dilute a solution, it becomes more and more like pure water. So the pH moves closer to the pH of pure water, pH 7. The pH decreases on dilution.
What is the pH of a 10⁻³ mol/L solution of NaOH? What is the pH if you dilute 100 mL of this solution to 1 L?
pOH = -log[OH⁻] = -log(10⁻³) = 3.
pH = 14 – pOH = 14 – 3 = 11.
pOH = -log[OH⁻] = -log(10⁻⁴) = 4.
pH = 14 – pOH = 14 – 4 = 10.
The pH has decreased from 11 to 10.
The pH of a basic solution decreases on dilution.