What type of substance increases the concentration of hydroxyl ions when dissolved in water?

• A. Acid
• B. Base
• C. Neutral
• D. Buffer

Answer: (B)

A substance that increases the concentration of hydroxyl ions (OH-) when dissolved in water is classified as a base. Bases are known for their ability to dissociate in solution to produce hydroxide ions, which leads to an increase in the pH of the solution, making it more alkaline.

When a base dissolves in water, it contributes to the overall ion concentration by releasing hydroxide ions. This property is central to the definition of bases in the context of the Brønsted-Lowry theory, where they are considered proton acceptors.

In practical terms, common examples of bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH), both of which readily dissociate in water to yield hydroxide ions.

Understanding the characteristics of bases is essential in clinical chemistry, as the pH of biological fluids can significantly influence metabolic processes and the functioning of various enzymes and biomolecules.