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Question
What are drying or desiccating agents? Give examples.
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Solution
These are substances which can readily absorb moisture from other substances without chemically reacting with them.
Examples:
Phosphorous pentoxide (P2O5), quick lime (CaO)
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RELATED QUESTIONS
Give two examples of Crystalline anhydrous substances.
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.
Complete the statement by filling the blank with the correct word from the option.
Hygroscopic substance absorb moisture from the atmosphere & _______their original state.
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.
Differentiate between the following:
Deliquescent salt and hygroscopic salt
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.
A hot saturated solution of copper sulphate forms crystals as it cools. Why?
'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.
