What term describes a solution with a high concentration of hydroxide ions?

A solution characterized by a high concentration of hydroxide ions is described as a basic solution. In the context of acid-base chemistry, a basic solution has a pH greater than 7, indicating that it has an excess of hydroxide ions (OH⁻). This occurs because bases are substances that can either provide hydroxide ions when dissolved in water or accept protons (H⁺) from acids.

The presence of a high concentration of hydroxide ions results in characteristic properties such as a bitter taste and a slippery feel, commonly associated with substances like soap. Additionally, basic solutions can neutralize acids, which is a central concept in understanding acid-base reactions.

Other types of solutions, such as acidic or neutral solutions, do not exhibit this elevated concentration of hydroxide ions. Acidic solutions contain a higher concentration of hydrogen ions (H⁺) and have a pH lower than 7, while neutral solutions have equal concentrations of hydrogen and hydroxide ions, resulting in a pH of 7. Non-aqueous solutions, on the other hand, refer to solutions not involving water as the solvent and do not pertain specifically to the discussion of ion concentrations in relation to pH.