Acidic oxide

An acidic oxide is an oxide that either produces an acidic solution upon addition to water, or acts as an acceptor of hydroxide ions effectively functioning as a Lewis acid.^[1] Acidic oxides will typically have a low pK_a and may be inorganic or organic. A commonly encountered acidic oxide, carbon dioxide produces an acidic solution (and the generation of carbonic acid) when dissolved.^[2]

The acidity of an oxide can be reasonably assumed by its accompanying constituents. Less electronegative elements tend to form basic oxides such as sodium oxide and magnesium oxide, whereas more electronegative elements tend to produce acidic oxides as seen with carbon dioxide and phosphorus pentoxide. Some oxides like aluminium oxides are amphoteric.^[3]

Acidic oxides are of environmental concern. Sulfur and nitrogen oxides are considered air pollutants as they react with atmospheric water vapour to produce acid rain.

^ John Daintith (February 2008). "acidic". A Dictionary of Chemistry. 3. Describing a compound that forms an acid when dissolved in water. Carbon dioxide, for example, is an acidic oxide.
^ David Oxtoby; H. P. Gillis; Alan Campion. Principles of Modern Chemistry (7th ed.). Cengage Learning. pp. 675–676. ISBN 978-0-8400-4931-5.
^ Chang, Raymond; Overby, Jason (2011). General chemistry: the essential concepts (6th ed.). New York, NY: McGraw-Hill. ISBN 9780073375632. OCLC 435711011.

[1] John Daintith (February 2008). "acidic". A Dictionary of Chemistry. 3. Describing a compound that forms an acid when dissolved in water. Carbon dioxide, for example, is an acidic oxide.

[2] David Oxtoby; H. P. Gillis; Alan Campion. Principles of Modern Chemistry (7th ed.). Cengage Learning. pp. 675–676. ISBN 978-0-8400-4931-5.

[3] Chang, Raymond; Overby, Jason (2011). General chemistry: the essential concepts (6th ed.). New York, NY: McGraw-Hill. ISBN 9780073375632. OCLC 435711011.

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