The pH of a solution measures its acidity or basicity. The pH of pure water is 7.0. A solution is more acidic than pure water if it is less than 7.0, and more basic than pure water if it is greater than 7.0. A solution of 0.1 M KCl has a pH of 6.9. A solution of 0.1 M NaCl has a pH of 7.0. A solution can be more alkaline than pure water if it is more than 7.0, and be more acidic than pure water if it is less than 7.0. A solution of 0.1 M NaOH has a pH of 11.0. A solution of 0.1 M HCl has a pH of 1.0.