sulphur trioxide

British  

noun

1. Systematic name: sulphur(VI) oxide.  a white corrosive substance existing in three crystalline forms of which the stable ( alpha- ) form is usually obtained as silky needles. It is produced by the oxidation of sulphur dioxide, and is used in the sulphonation of organic compounds. Formula: SO 3

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Example Sentences

Such oxides as sulphur trioxide, nitrogen pentoxide, etc., do not possess acid properties except in combination with water.

From Project Gutenberg

The olefines—ethylene, &c.—are generally absorbed by a very strong sulphuric acid prepared by adding sulphur trioxide to sulphuric acid to form a mixture which solidifies when slightly cooled.

From Project Gutenberg

Chief culprits in the Donora, London and New York smog disasters were probably sulphur dioxide and sulphur trioxide, which, either in gaseous form or converted into sulphuric-acid mist, can irritate the skin, eyes and upper respiratory tract.

From Time Magazine Archive

It is not volatile below a white heat, and consequently, if heated with salts of more volatile acids, it expels the acid forming oxide from such salts; for example, if potassium sulphate be heated with boron trioxide, sulphur trioxide is liberated and potassium borate formed.

From Project Gutenberg

The acid commonly used is made by the "contact" process, in which sulphur dioxide is oxidized to sulphur trioxide, and then, with the addition of water, changed to sulphuric acid.

From Project Gutenberg