Here's why:
* Arrhenius definition of bases: A base is a substance that increases the concentration of hydroxide ions (OH-) when dissolved in water.
* Brønsted-Lowry definition of bases: A base is a substance that accepts a proton (H+). Hydroxide ions are good proton acceptors, forming water (H2O).
Examples:
* Sodium hydroxide (NaOH): Dissolves in water to form sodium ions (Na+) and hydroxide ions (OH-).
* Potassium hydroxide (KOH): Dissolves in water to form potassium ions (K+) and hydroxide ions (OH-).
* Calcium hydroxide (Ca(OH)2): Dissolves in water to form calcium ions (Ca2+) and hydroxide ions (OH-).
While hydroxide ions are the most common indicator of bases, other ions can act as bases in specific circumstances, particularly when considering the Brønsted-Lowry definition.
