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Organic Chemistry – Some Basic Principles And Techniques

Question

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Why is it necessary to boil the Lassaigne's extract with concentrated nitric acid before testing for halogens?

Solution

The function of nitric acid: If nitrogen and sulphur are also present along with halogens in the organic compound, the Lassaigne’s filtrate will contain sodium cyanide (NaCN) and sodium sulphide (Na₂S) in addition to sodium halide. Concentrated nitric acid decomposes both sodium cyanide as well as sodium sulphide which otherwise form white and black precipitate respectively with silver nitrate.

NaCN space plus space HNO subscript 3 space space rightwards arrow space space NaNO subscript 3 space plus space HCN upwards arrow Na subscript 2 straight S space plus space 2 HNO subscript 3 space rightwards arrow space space 2 NaNO subscript 3 space plus space straight H subscript 2 straight S space upwards arrow

Some More Questions From Organic Chemistry – Some Basic Principles and Techniques Chapter

What system of nomenclature is accepted universally?

What are isomers?

How many chain isomers are possible for pentane?

Which characteristic is common to different isomers of a compound?

Name three alkanes which do not show chain isomerism.

Name the types of structural isomerism shown by alkanes.

Name the four main types of structural isomerism.

Write the three possible open chains of five carbon atoms

What types of structural isomerism is shown by the following pairs of organic compounds ?

Write the tautomer of acetaldehyde and write its IUPAC name.

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