A strong base is a basic chemical compound that is able to deprotonate very weak acids in an acid-base reaction. The strength of a base is indicated by its pK_b value, compounds with a pK_b of more than about 13 are called strong bases. Common examples of strong bases are the hydroxides of alkali metals and alkaline earth metals like NaOH and Ca(OH)₂. In water strong bases form hydroxyl ions (OH^-), either by complete dissociation through solvation (metal hydroxides) or by chemical reaction with water (e.g. NaH and LDA).

The general reaction of a base with water is:

A^-_(aq) + H₂O_(l) ↔ HA_(aq) + OH^-_(aq)

Very strong bases are even able to deprotonate very weakly acidic C-H groups in the absence of water.

Common examples

Strong base Ionisers

(Strongest to weakest)

• Potassium hydroxide (KOH)
• Barium hydroxide (Ba(OH)₂)
• Cesium hydroxide (CsOH)
• Sodium hydroxide (NaOH)
• Strontium hydroxide (Sr(OH)₂)
• Calcium hydroxide (Ca(OH)₂)
• Lithium hydroxide (LiOH)
• Rubidium hydroxide (RbOH)

Basically, the cations of these strong bases appear in the 1st and 2nd groups of the Periodic Table (Alkali and Alkali-Earth Metals).

Extremely Strong Base Ionisers

• Sodium hydride (NaH)
• Lithium diisopropylamide (LDA) (C6H14LiN)
• Sodium amide (NaNH₂)

See also

• Acid-base reaction theories
• Base
• Acid

External links

Bases

Sterke base