Preparation and purification of organic compounds Quiz
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5 questions, one answer each
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1. What does a pure solid show when its melting temperature is measured?
- A. A sharp range at the literature value
- B. A wide range below the literature value
- C. A wide range above the literature value
- D. No melting at all
2. Which is the correct drying agent?
- A. Dilute sulfuric acid
- B. Aqueous sodium chloride
- C. Ethanol
- D. Anhydrous magnesium sulfate
3. A compound decomposes when heated to its boiling temperature and is immiscible with water. Which method separates it from tar?
- A. Reflux
- B. Simple distillation
- C. Steam distillation
- D. Recrystallisation
4. In recrystallisation, why must the solution be cooled slowly?
- A. So that pure crystals form and impurities remain dissolved
- B. So the solvent evaporates
- C. So that the solid decomposes
- D. So that the melting temperature rises
5. 2.50 g of salicylic acid (M = 138.0) gives 2.00 g of aspirin (M = 180.0). What is the yield?
- A. 80.0%
- B. 61.3%
- C. 55.0%
- D. 88.3%