Page 32 - Curriculum Visions Dynamic Book

Sulphates and sulphites
Sulphates are compounds containing sulphur and oxygen. Sulphites are compounds of sulphur containing less oxygen than sulphates.
There is a wide range of sulphates, usually formed by a combination of
a metal (such as calcium, magnesium or sodium, as shown on this page,
or copper as shown on page 34).
Sulphate salts are formed in the laboratory by reacting sulphuric acid on a metal, oxide, hydroxide or carbonate.
Most sulphates are soluble in water.
Magnesium sulphate
Magnesium sulphate was first made by evaporating mineral water from a spring near a town called Epsom in Surrey, England. For this reason it is also called Epsom salts.
Epsom salts act as a laxative by preventing the water in the intestine from being absorbed in the body. The result is that there is more water than usual in the intestine, which sets the action of the bowels in motion.
Concentrated Epsom salts are used to stop inflammation and to prevent convulsions. They are also used in both dyeing and bleaching processes, as part of fertilisers, and in matches and explosives. They can also have a fireproofing effect.
 Sulphates and their properties.
 Gypsum is used for plastering in the construction industry.
Calcium sulphate
One of the most common sulphate minerals in the Earth’s rocks is calcium sulphate, also known as gypsum. One form of gypsum is alabaster which, being soft, is easily machined to make ornaments such as candlesticks.
Gypsum is formed in the bottom
of saline lakes. As the lake water evaporates, the chemicals dissolved in it become progressively more concentrated until the solution becomes saturated and crystals begin to form.
Crushed gypsum is used as Plaster of Paris and is made into wallboards (it is the smooth surface of the interiors of walls).
Sulphate
Common name
Application
Calcium sulphate
Gypsum
Soil conditioner, plasterboard
Plaster of Paris
Casts (used to set broken limbs)
Barium sulphate
Barite
Drilling mud in oil fields, digestion, X-rays
Sodium sulphate
Glauber’s salt
Glass-making
Lead sulphate
Produced as lead-acid battery discharges
Copper sulphate
Blue vitriol
Fungicide (Bordeaux mixture)
Iron sulphate
Green vitriol
Lawn care
Magnesium sulphate
Epsom salts
Laxative
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