Base anhydride

 ( Acid–base Chemistry ) 

A base anhydride is an oxide of a chemical element from group 1 or 2 (the and alkaline earth metals, respectively). They are obtained by removing water from the corresponding hydroxide base. If water is added to a base anhydride, a corresponding hydroxide salt can be re-formed.

Base anhydrides are Brønsted–Lowry bases because they are proton acceptors. In addition, they are , because they will share an electron pair with some Lewis acids, most notably .Principles of Modern Chemistry, 7th Edition. David Oxtoby, H. P. Gillis, Alan Campion. Published by Cengage Learning. Page 675-676. They are potent and will produce chemical burn on skin, because their affinity for water (that is, their affinity for being ) makes them react with body water.

• Quicklime (calcium oxide) is a base anhydride. It reacts with water to become hydrated lime (calcium hydroxide),Collie, Robert L. "Solar heating system" issued May 11, 1976 which is a strong base, chemically akin to lye. This reaction is exothermic.

:CaO + H₂O → Ca(OH)₂ (ΔH_r = −63.7kJ/mol of CaO)

• Sodium oxide is a very strong base that reacts readily and irreversibly with water to give sodium hydroxide:

: Na₂O + H₂O → 2 NaOH

• Acid anhydride
• Acidic oxide