Question

Why is HNO3 acid added to sodium extract before adding AgNO3 for testing halogens

Answer 1

If organic compound contains Nitrogen, sulphur and halogens the nitrogen and sulphur create the problem in the identification of halogens. both will form NaCN and Na2S on fusion with sodium metal. and both these compounds reacts with silver nitrate to give precipitate. These precipitates interfere with the precipitates of halogens. to avoid this nitric acid is added to the sodium extract. this nitric acid destroy  NaCN and Na2S compounds to form volatile gases


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