ChemistryAdvancedHigh School (11–12)Organic Chemistry: Some Basic Principles and Techniques › Purification and Analysis of Organic CompoundsNEETJEE Main
Created by StemPy LabThe figure shows tests on a sodium fusion extract and what was seen. Read these conclusions. (i) Tube 1 shows nitrogen; the blue colour is iron(III) hexacyanidoferrate(II). (ii) The violet colour in Tube 4 comes from thiocyanate ions. (iii) Tube 3 shows chlorine; bromine would give a pale yellow precipitate. (iv) Nitric acid in Tube 3 removes cyanide and sulphide, which would also react with silver nitrate. (v) With sulphur present, the Prussian blue shows that too little sodium was used. How many of the statements above are correct?
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← A student separates a mixture by column chromatography and checks the fractions by thin layer chromatography. Two statements about these methods are given below.
Statement I: In column chromatography, the component that is adsorbed most strongly on the alumina or silica gel moves fastest down the column and is collected first.
Statement II: Spots of colourless compounds on a thin layer plate can be seen under ultraviolet light, or by putting the plate in a covered jar with a few crystals of iodine.Assertion (A): A student fuses hydrazine, N₂H₄, with sodium, as in Lassaigne's test, and boils the extract with iron(II) sulphate and then acid. Although hydrazine contains nitrogen, no Prussian blue colour appears. Reason (R): In the fusion, nitrogen is changed to sodium cyanide only together with carbon from the compound: Na + C + N → NaCN. →
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