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Examine Fig. 5.26.
(i) Identify the separation technique marked as ‘S’.
(ii) Label the apparatus A, B and C.
(iii) Which of the following mixtures can be separated by the technique identified above? Use the data given in Table 5.5. Mixtures:
(a) water — acetone (b) water — salt
(c) acetone — alcohol (d) sand — salt
(e) alcohol — chloroform (f) alcohol — benzene
(i) Identify the separation technique marked as ‘S’.
(ii) Label the apparatus A, B and C.
(iii) Which of the following mixtures can be separated by the technique identified above? Use the data given in Table 5.5. Mixtures:
(a) water — acetone (b) water — salt
(c) acetone — alcohol (d) sand — salt
(e) alcohol — chloroform (f) alcohol — benzene
View Answer
(i) The technique 'S' is distillation . (ii) A is the distillation flask, B is the water condenser, and C is the conical flask that collects the distillate.
(iii) Distillation works when boiling points differ by about 25 °C or more. From Table 5.5 (Water 100, Acetone 56, Alcohol 78, Chloroform 61, Benzene 80): water–acetone (gap 44 °C) and water–salt (a dissolved solid in liquid) can be separated. Acetone–alcohol (22 °C), alcohol–chloroform (17 °C) and alcohol–benzene (2 °C) have gaps too small for simple distillation; sand–salt is a solid–solid mixture, not separated by distillation.
| Mixture | Boiling points | Separable by distillation? |
|---|---|---|
| (a) water — acetone | 100 °C and 56 °C → gap 44 °C | Yes — gap is well over 25 °C |
| (b) water — salt | salt is a dissolved solid | Yes — the water distils over, the salt stays in the flask |
| (c) acetone — alcohol | 56 °C and 78 °C → gap 22 °C | No — gap is under 25 °C |
| (d) sand — salt | a solid–solid mixture | No — nothing to vaporise; use dissolving and filtration |
| (e) alcohol — chloroform | 78 °C and 61 °C → gap 17 °C | No — gap is under 25 °C |
| (f) alcohol — benzene | 78 °C and 80 °C → gap 2 °C | No — boiling points are almost the same |
