The technique used for purification of steam volatile water immiscible substances is: [2024]
frictional distillation
fractional distillation under reduced pressure
distillation
steam distillation
(D)
Process of steam distillation is used for its purification. The vapours of steam and the liquid compound come out of the heated flask and are condensed and collected in a separate flask. As the liquid is immiscible with water (in liquid phase), these two form separate layers and are separated using a separating funnel.
Chromatographic technique/s based on the principle of differential adsorption is/are
A. Column chromatography
B. Thin layer chromatography
C. Paper chromatography
Choose the most appropriate answer from the options given below: [2024]
B only
A only
A and B only
C only
(C)
On the basis of differential adsorption, chromatographic techniques are of two types:
Column chromatography and thin layer chromatography.
Which among the following purification methods is based on the principle of "Solubility" in two different solvents? [2024]
Column Chromatography
Sublimation
Distillation
Differential Extraction
(D)
An organic compound present in an aqueous solution along with other ionic impurities is separated by the principle of differential extraction. For this method a suitable organic solvent is chosen which is immiscible in water. This solvent is added to the aqueous solution containing the organic compound. Organic compound has more solubility in the organic solvent than in water, hence is transferred from water to the organic solvent. Other ionic impurities in aqueous solution remain in water.
‘Adsorption’ principle is used for which of the following purification method? [2024]
Chromatography
Sublimation
Extraction
Distillation
(A)
Adsorption chromatography is based on the fact that different compounds are adsorbed on an adsorbent to different degrees.
Match List I with List II
| LIST I (Technique) | LIST II (Application) | ||
| A. | Distillation | I. | Separation of glycerol from spent-lye |
| B. | Fractional distillation | II. | Aniline - Water mixture |
| C. | Steam distillation | III. | Separation of crude oil fractions |
| D. | Distillation under reduced pressure | IV. | Chloroform - Aniline |
Choose the correct answer from the options given below: [2024]
A-IV, B-I, C-II, D-III
A-IV, B-III, C-II, D-I
A-I, B-II, C-IV, D-III
A-II, B-III, C-I, D-IV
(B)
| Separation technique | Application |
| Distillation | Chloroform (b.p 334 K) and aniline (b.p. 457 K) |
| Fractional distillation | Different fractions of crude oil in the petroleum industry are separated by fractional distillation. |
| Steam distillation | Aniline is separated by this technique from aniline–water mixture |
| Distillation under reduced pressure | Glycerol is separated from spent-lye in the soap industry. |
The fragrance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for the extraction of these oils from the flowers is: [2024]
distillation
crystallisation
steam distillation
distillation under reduced pressure
(C)
Steam distillation is applied to separate substances which are steam volatile and are immiscible with water. Thus essential oils are extracted from flowers using this technique.
The adsorbent used in adsorption chromatography is/are
A. silica gel
B. alumina
C. quick lime
D. magnesia
Choose the most appropriate answer from the options given below: [2024]
C and D only
A only
A and B only
B only
(C)
Silica gel and alumina are used as adsorbents in adsorption chromatography.
Which of the following statements are correct?
(A) Glycerol is purified by vacuum distillation because it decomposes at its normal boiling point.
(B) Aniline can be purified by steam distillation as aniline is miscible in water.
(C) Ethanol can be separated from ethanol-water mixture by azeotropic distillation because it forms azeotrope.
(D) An organic compound is pure, if mixed M.P. is remained the same.
Choose the most appropriate answer from the options given below: [2024]
B, C, D only
A, C, D only
A, B, C only
A, B, D only
(B)
Aniline can be purified by steam distillation as aniline is immiscible in water.
The correct statements among the following, for a "chromatography" purification method is: [2024]
Non-polar compounds are retained at the top and polar compounds come down in column chromatography.
Organic compounds run faster than solvent in the thin layer chromatographic plate.
of a polar compound is smaller than that of a non-polar compound.
is an integral value.
(C)
More polar compounds are absorbed more in chromatography hence have lower than less polar compounds. Those compounds which are adsorbed more (i.e. more polar) are retained at top. Solvent is not adsorbed, so solvent runs fastest in chromatography.
Methods used for purification of organic compounds are based on: [2024]
Nature of compound and presence of impurity.
Presence of impurity only.
Neither on nature of compound nor on the impurity present.
Nature of compound only.
(A)
Various methods used for the purification of organic compounds are based on the nature of the compound and the impurity present in it.
