Acidic oxide

Acidic oxides are oxides that react with water forming an acid; or react with a base forming a salt. They are oxides of either nonmetals or of metals in high oxidation states. They are formed when a nonmetal burns. Their chemistry can be systematically understood by taking an oxoacid and removing water from it, until only the oxide is left. The resulting oxide belongs to this group of substances.

Acidic oxides are not Arrhenius acids because they do not donate protons; they are not Brønsted–Lowry acids because they do not increase the hydrogen ion concentration of water. However, they are Lewis acids, because they accept electron pairs from some Lewis bases, most notably base anhydrides.^[1]

Examples

• Carbon dioxide, which reacts with water forming carbonic acids
• Sulfur dioxide, which does not react with water forming the non-existent sulfurous acid but does react with bases forming sulfites
• Silicon dioxide, which does not react with water but does react with bases forming silicates
• Chromium trioxide, which reacts with water forming chromic acid
• Phosphorus pentoxide, which reacts with water forming phosphoric acid
• Dinitrogen pentoxide, which reacts with water forming nitric acid
• Sulfur trioxide, which reacts with water forming sulfuric acid
• Manganese heptoxide, which reacts with water forming permanganic acid
• Dichlorine monoxide, which slowly reacts with water forming hypochlorous acid

See also

• Organic acid anhydride, similar compounds in organic chemistry
• Base anhydride
• Inorganic anhydride (or anhydride or acid anhydride)

References

• Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.

1. Principles of Modern Chemistry, 7th Edition. David Oxtoby, H. P. Gillis, Alan Campion. Published by Cengage Learning. Page 675-676. ISBN 978-0840049315