Same chapter3 marksDifficulty: Medium
The solubility of potassium nitrate at 30 °C is 45 g per 100 g of water. What mass of the salt will saturate 250 g of water at that temperature?
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3 marksDifficulty: Medium
Distinguish between a hydrated and an anhydrous salt, and state what happens when blue copper sulphate crystals are heated.
Original Khojo Papers practice question — not from a past board paper.
Answer
A hydrated salt contains water of crystallisation chemically combined with it, while an anhydrous salt contains none. On heating, blue copper sulphate crystals lose their five molecules of water and turn into a white anhydrous powder; adding water turns them blue again.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
This colour change is used as a test for water.
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