How do classify the behaviour of water as an acid?

1 Answer
anor277
May 25, 2017

Water is an "amphoteric species" according to the "Bronsted Lowry concept."

Explanation:

According to the "Lewis concept", water is also amphoteric.

A Lewis acid is defined as an electron-pair acceptor; and a Lewis base in an electron pair donor. Water's dual classification can be appreciated from the autoprotolysis reaction of water:

2H_2O(l) rightleftharpoonsH_3O^(+)+HO^(-)

While this (carefully measured!) equilibrium lies strongly to the left, water has clearly acted as a Lewis base to give the "hydronium ion", and as a Lewis acid to give the "hydroxide ion".

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