Question

Pure water has a hydrogen ion concentration of 1 × 10−7 M and a pH of 7. A student measures a basic solution and finds that it has a hydrogen ion (H+) concentration of 1 × 10−3. Explain why the student must have made an error in her measurement.

Answer 1

because the pH of a basic solution must be greater than 7 \[pH=-\log [H+]\]

Answer 2

[H+]{OH-} = 10^-14 approx.