How is the concentration of hydroxide ions (OH–) affected when excess base is dissolved in a solution of sodium hydroxide?

When excess base, such as sodium hydroxide (NaOH), is dissolved in a solution, the concentration of hydroxide ions (OH⁻) increases. This is because sodium hydroxide dissociates in water to form sodium ions (Na⁺) and hydroxide ions (OH⁻) according to the following equation:

NaOH → Na⁺ + OH⁻ NaOH → Na⁺ + OH⁻
As more sodium hydroxide is added to the solution, more hydroxide ions are produced. The concentration of hydroxide ions is directly proportional to the concentration of the dissolved sodium hydroxide. If you add excess sodium hydroxide, the concentration of hydroxide ions will continue to rise.

It’s important to note that the concentration of hydroxide ions in a solution is related to its pH. The higher the concentration of hydroxide ions, the more basic (or alkaline) the solution becomes. The pH scale is a logarithmic scale that measures the acidity or basicity of a solution, with values ranging from 0 (very acidic) to 14 (very basic). Excess sodium hydroxide will raise the pH of the solution.