When a base dissolves in water, it disassociates into positive and negative ions. Many bases are composed of a metal ionically bonded with one or more hydroxide ions (`~OH^-` ). When a base containing hydroxide dissolves in water, it breaks apart into positively charged metal ions and negatively charged hydroxide ions.
Bases that produce `~OH^-` ions in water are called Arrhenius bases. Examples of Arrenius bases include: NaOH, KOH, and `~Ca(OH)_2` . When dissolved in water, these bases disassociate into ions as follows:
NaOH(s) -> `~Na^+(aq) ` + `~OH^-_(aq)``<br> `
KOH(s) -> `~K^+(aq)` + `~OH^- _(aq)`
`~Ca(OH)_2`(s) -> `~Ca^2^+(aq)` + `~2OH^- _(aq)`
Bases that completely disassociate into ions are classified as strong bases. Weak bases disassociate into ions incompletely. This means that only some of the base disassociates into ions while the rest remains as a neutral compound.
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