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Question
Explain the following observation:
Why is fused calcium chloride or cone, sulphuric acid used in a desiccator?
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Solution
Anhydrous or fused calcium chloride is highly hygroscopic in nature it readily absorbs moisture, also it is deliquescent in nature and is therefore used as a drying agent in a desiccator.
Concentrated sulphuric acid being hygroscopic in nature absorbs moisture from the air and gets diluted and acts as a drying agent as well as a dehydrating agent and hence is used in a desiccator.
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RELATED QUESTIONS
Give the names and formulae of two substances
Anhydrous substance
The substance that can remove hydrogen and oxygen atoms in the ratio of 2:1(in the form of water) from the compound.
State the methods by which hydrated salts can be made anhydrous.
Name three methods by which hydrous substances can be made anhydrous.
Differentiate between an efflorescent, deliquescent & ‘ hygroscopic substance with suitable examples.
Match the substances in List I with the appropriate answer in List II.
| List I | List II |
| 1. Green vitriol | A: Permanent hardness in water |
| 2. Paint | B: Hygroscopic |
| 3. Magnesium chloride | C: Temporary hardness in water |
| 4. Magnesium bicarbonate | D: Heptahydrate |
| 5. Calcium oxide | E: Colloidal |
Match the following
| 1. | Blue vitriol | CaSO4.2H2O |
| 2. | Gypsum | CaO |
| 3. | Deliquescence | CuSO4.5H2O |
| 4. | Hygroscopic | NaOH |
The molecular formula of green vitriol is MgSO4.7H2O.
Define Hydrated salt.
'A' is a blue coloured crystalline salt. On heating, it loses blue colour and to give 'B'. When water is added, 'B' gives back to 'A'. Identify A and B, write the equation.
