Sulphur-Industrial and inorganic chemistry
The characteristics of sulphur
|Colour||Sulphur is a yellow coloured element.|
|Metallic or non-metallic?||It is a non-metallic element.|
|Group||It is found in group VI of the periodic table.|
|Electrical conductivity||It doesn’t conduct electricity.|
|Allotropes of sulphur||Rhombic and Monoclinic sulphur|
|Strenght||It is a brittle element|
|Where is sulphur found?||It is found in metallic ores such as:
It is also found in crude oil and natural gas. This needs to be removed or else it may cause environmental problems. Sulphur obtained from these products is called as recovered sulphur.
It is found native in underground beds in the USA, Mexico, Russia and Poland.
|Method of extracting sulphur||It is extracted using the Frasch process.
Uses of Sulphur
- Sulphur is used to produce sulphuric acid
- It is used to vulcanise rubber
- It is used in the manufacture of matchsticks, fireworks and fungicides
- Moreover, It is also used as a sterilising agent and in medicines
|Colour||Sulphur dioxide is a colourless and poisonous gas|
|Sulphur dioxide is produced when||Substances containing sulphur are burned in oxygen gas|
|When Sulphur dioxide is dissolved in water,||It forms an acidic solution of sulphurous acid (H2SO3), which turns moist pH paper change colour to red.|
|Odour (smell)||It has a choking, pungent smell.|
|Test for sulphur dioxide||When dissolved, Sulphur dioxide changes the colour of acidified potassium (VII) manganate from purple to colourless.|
|Uses of Sulphur dioxide|
|Sulphur dioxide is used as a bleaching agent for paper manufacturing.||It is used as a preservative.|
|Moreover, It is used as a fumigant.||Furthermore, It is also used to kill bacteria in order to preserve food.|
Most of the sulphur extracted is used in the manufacturing of sulphuric acid. Let us see how this is done!
Sulphuric acid is manufactured using the contact process.
|Important conditions of the contact process|
|Catalyst||Vanadium (V) oxide (V2O5)|
|Atmospheric pressure||1-2 atm|
|Sulphur is burnt in oxygen to form sulphur dioxide||S(s) + O2(g) + SO2(g)|
|Sulphur dioxide is mixed with more oxygen to form Sulphur trioxide||2SO2(g)+ O2(g) + 2SO3(g)|
|Sulphur trioxide needs to be mixed with water to form sulphuric acid; but this is not done as it can cause an acidic mist to form and damage the environment.
Instead, Sulphur trioxide undergoes the following process:
|Sulphur trioxide is dissolved in concentrated sulphuric acid. This results in the formation of a substance called oleum.||SO3(g) + H2SO4(l) à H2S2O7(l)
|Finally, add water to Oleum. This results in sulphuric acid being produced||H2S2O7(l) + H2O(l) à H2SO4(l)|
Uses of concentrated sulphuric acid
Concentrated sulphuric acid is used:
- for making detergents
- as a catalyst
- as a dehydrating agent
Uses of dilute sulphuric acid
Dilute sulphuric acid is used:
- For making fertilizers.
- To treat metals to remove oxidisation before painting.
- For anodising aluminium.
- As an acid in car batteries.
- For manufacturing paints, dyes and fibres.
- As a common laboratory reagent
The salts of sulphuric acid are called sulphates.
Sulphates can be identified by a simple test-tube reaction. To test for the presence of a sulphate, add a few drops of dilute hydrochloric acid to your unknown followed by a few drops of barium chloride.
If a sulphate is present, a white precipitate of barium sulphate forms.
Properties of sulphuric acid
Concentrated sulphuric acid is a very corrosive substance.
|Dilute sulphuric acid||Concentrated sulphuric acid|
|Dilute sulfuric acid is a typical strong dibasic acid.||Concentrated sulphuric acid is a powerful dehydrating agent.|
|A dibasic acid is one with two replaceable hydrogen
atoms which may produce two series of salts –
normal and acid salts
|Concentrated sulphuric acid is used to dry gases (except ammonia).||Concentrated sulphuric acid is a powerful oxidising agent.||Concentrated sulphuric acid can be used to produce nitric and hydrochloric acid.|
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