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प्रश्न
Differentiate between hydrated and anhydrous crystals with examples. State three defined changes that occur when hydrated copper sulphate is heated.
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उत्तर
Difference between hydrated and anhydrous crystals:
| Hydrated crystal | Anhydrous crystal |
| (i) Contains fixed number of water molecules. | (i) Does not contains any fixed number of water molecules |
| (ii) CuSO4, 5H2O, FeSO4.7H2O are examples. | KNO3, K2SO4 are examples. |
Three defined changes: When CuSO4. 5H2O is heated take place are: (blue).
- Colour changes from blue to colourless.
- Changed to AMORPHOUS white powder
- Geometric shape vanishes
- On cooling and adding water colour restores but crystalline does not shape.
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संबंधित प्रश्न
The sticky substance formed when soap is added to hard water is ______.
Give one word for the following statement:
Water molecules in loose chemical combination with other substances.
Give the names and formulae of two substances
Anhydrous substance
What are drying or desiccating agents? Give examples.
Complete the following table:
|
Common Name |
Chemical Name |
Formula |
Acid, base or salt |
Efflorescent, hygroscopic or deliquescent substance |
|
Solid caustic potash |
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|
|
|
|
Quick lime |
|
|
|
|
|
Oil of vitriol |
|
|
|
|
|
Washing soda |
|
|
|
|
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Solid caustic soda |
|
|
|
|
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Blue vitriol |
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|
State the methods by which hydrated salts can be made anhydrous.
What are hydrous substances? Explain with examples.
The process of separation or deposition of crystals from a hot saturated solution on gentle cooling of the solution is called ‘crystallization’. With reference to the statement explain what is meant by ‘water of crystallization. State which physical properties of a crystal are correlated with the water of crystallization.
Differentiate between ‘hydrated’ & ‘anhydrous’ crystals. Give the chemical formula of – the following hydrated crystals -
(a) Washing soda
(b) Gypsum
(c) Blue vitriol
(d) Epsom salt
(e) Glauber’s salt.
State which crystal from (a) to (e) is a pentahydrate.
Select the correct answer from the choice given in the options.
An anhydrate of a heptahydrate salt _____.
