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Sodium extract is heated with con. HNO(3...

Sodium extract is heated with con. `HNO_(3)` before testing for halogens because

A

`Ag_(2)S and AgCN` are soluble in acidic medium.

B

Silver halides are totally insoluble in nitric acid.

C

`S^(2-) and CN^(-)`, if present, are decomposed by conc. `HNO_(3)` and hence do not interfere in the test.

D

Ag reacts faster with halides in acidic medium

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To solve the question regarding why sodium extract is heated with concentrated HNO3 before testing for halogens, we can break down the reasoning step by step. ### Step-by-Step Solution: 1. **Understanding Sodium Extract**: - Sodium extract is obtained by heating sodium metal with an organic compound. During this process, sodium reacts with elements in the compound, potentially forming sodium sulfide (Na2S), sodium cyanide (NaCN), and sodium halides (NaX, where X is a halogen). 2. **Formation of Compounds**: - When sodium reacts with sulfur, it can form Na2S. - If nitrogen is present, it can form NaCN. - If halogens are present, they can form sodium halides (NaX). 3. **Testing for Halogens**: - To test for halogens, we typically use silver nitrate (AgNO3) to precipitate silver halides (AgX), which are insoluble in water. 4. **Interference from Sulfide and Cyanide**: - In the sodium extract, if sulfide ions (S2-) or cyanide ions (CN-) are present, they can interfere with the test for halogens. - For example, silver sulfide (Ag2S) and silver cyanide (AgCN) can form, which would complicate the results. 5. **Role of Concentrated HNO3**: - Heating the sodium extract with concentrated HNO3 helps to oxidize and decompose the sulfide and cyanide ions. - This reaction converts S2- to sulfuric acid (H2SO4) and CN- to hydrogen cyanide (HCN), which are volatile and do not interfere with the halogen test. 6. **Final Outcome**: - By treating the sodium extract with concentrated HNO3, we ensure that any potential interference from sulfide or cyanide ions is eliminated, allowing for a clear and accurate test for halogens using AgNO3. ### Conclusion: The sodium extract is heated with concentrated HNO3 to remove any interfering sulfide or cyanide ions, ensuring that the test for halogens is accurate and reliable.
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