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Question
What is meant by 'hydrated' and 'anhydrous' salts? Explain with examples.
Solution
Salts that contain water of crystallisation are called ‘hydrated salts’. For example, copper sulphate crystals contain five molecules of water of crystallisation in one formula unit and hence is written as CuSO4.5H2O. It is also called copper sulphate pentahydrate.
Salts that have lost their water of crystallisation on heating are called ‘anhydrous salts’. For example, when copper sulphate crystals (CuSO4.5H2O), which are blue, are heated strongly, they lose all the water of crystallisation and form anhydrous copper sulphate (CuSO4), which is white
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RELATED QUESTIONS
Write a balanced equation for the preparation of the following salts:
Copper sulphate from Copper Carbonate.
Explain how anhydrous copper sulphate can be used to detect the presence of moisture (water) in a liquid
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(d) seven
The aqueous solution of one of the following salts will turn phenolphthalein indicator pink. This salt is:
(a) KCl
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The Salt Story
From: The New Indian Express 9 March 2021
The salt pans in Marakkanam, a port town about 120 km from Chennai are the third largest producer of salt in Tamil Nadu. Separation of salt from water is a laborious process and the salt obtained is used as raw materials for manufacture of various sodium compounds.
One such compound is Sodium hydrogen carbonate, used in baking, as an antacid and in soda acid fire extinguishers.
The table shows the mass of various compounds obtained when 1litre of sea water is evaporated.
| COMPOUND | FORMULA | MASS OF SOLID PRESENT /g |
| Sodium Chloride | NaCl | 28.0 |
| Magnesium Chloride | MgCl2 | 8.0 |
| Magnesium Sulphate | MgSO4 | 6.0 |
| Calcium Sulphate | CaSO4 | 2.0 |
| Calcium Carbonate | CaCO3 | 1.0 |
| TOTAL AMOUNT OF SALT OBTAINED | 45.0 | |
How many grams of Magnesium Sulphate are present in 135g of solid left by evaporation of sea water?
The Salt Story
From: The New Indian Express 9 March 2021
The salt pans in Marakkanam, a port town about 120 km from Chennai are the third largest producer of salt in Tamil Nadu. Separation of salt from water is a laborious process and the salt obtained is used as raw materials for manufacture of various sodium compounds.
One such compound is Sodium hydrogen carbonate, used in baking, as an antacid and in soda acid fire extinguishers.
The table shows the mass of various compounds obtained when 1litre of sea water is evaporated.
| COMPOUND | FORMULA | MASS OF SOLID PRESENT /g |
| Sodium Chloride | NaCl | 28.0 |
| Magnesium Chloride | MgCl2 | 8.0 |
| Magnesium Sulphate | MgSO4 | 6.0 |
| Calcium Sulphate | CaSO4 | 2.0 |
| Calcium Carbonate | CaCO3 | 1.0 |
| TOTAL AMOUNT OF SALT OBTAINED | 45.0 | |
What is the pH of the acid which is used in the formation of common salt?
Salt which is formed by the partial replacement of hydrogen ions of an acid by a metal is called ______.
