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प्रश्न
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.
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उत्तर
| Hydrated crystals | Anhydrous crystals |
| Hydrated crystals contain a definite number of water molecules (as water of crystallisation) in a loose chemical combination with the crystal. | Anhydrous crystals do not contain any definite number of water molecules in loose chemical combinations with the crystal. |
| E.g., CuSO4.5H2O | E.g., KNO3 |
The formula of hydrated crystals:
(a) Washing soda: Na2CO3.H2O
(b) Gypsum: CaSO4.2H2O
(c) Blue vitriol: CuSO4.5H2O
(d) Epsom salt: MgSO4.7H2O
(e) Glauber’s salt: Na2SO4.10H2O
Blue vitriol [CuSO4.5H2O] is a pentahydrate.
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संबंधित प्रश्न
Water turns the colour of anhydrous copper sulphate .................
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.
What are drying or desiccating agents? Give examples.
What are hydrous substances? Explain with examples.
Name three methods by which hydrous substances can be made anhydrous.
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.
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 |
Select the correct word from the words in option to complete the sentence:
Efflorescence occurs when the vapour pressure of the hydrated crystals is ____ than the vapour pressure of the atmospheric humidity.
'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.
