Class 11Chemistry3 Organic Chemistry: Purification and CharacterisationChemical analysis of organic compounds
MediumWhy is nitric acid added to sodium extract before adding silver nitrate for testing halogens?
(N/A) While testing the Lassaigne's extract for the presence of halogens,it is first boiled with dilute nitric acid.
This is done to decompose $NaCN$ to $HCN$ and $Na_{2}S$ to $H_{2}S$ and to expel these gases.
If nitrogen and sulphur are present in the form of $NaCN$ and $Na_{2}S$,they would interfere with the test for halogens by forming $AgCN$ and $Ag_{2}S$ precipitates,which are also insoluble in water.
The chemical equations involved in the reaction are:
$NaCN + HNO_{3} \longrightarrow NaNO_{3} + HCN \uparrow$
$Na_{2}S + 2HNO_{3} \longrightarrow 2NaNO_{3} + H_{2}S \uparrow$
This is done to decompose $NaCN$ to $HCN$ and $Na_{2}S$ to $H_{2}S$ and to expel these gases.
If nitrogen and sulphur are present in the form of $NaCN$ and $Na_{2}S$,they would interfere with the test for halogens by forming $AgCN$ and $Ag_{2}S$ precipitates,which are also insoluble in water.
The chemical equations involved in the reaction are:
$NaCN + HNO_{3} \longrightarrow NaNO_{3} + HCN \uparrow$
$Na_{2}S + 2HNO_{3} \longrightarrow 2NaNO_{3} + H_{2}S \uparrow$
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Similar Questions
The Lassaigne's extract is boiled with conc. $HNO_3$ while testing for halogens. By doing so it
MediumAIPMT 2011
View SolutionDiscuss the chemistry of Lassaigne's test.
Difficult
View SolutionGiven below are two statements :
Statement $I :$ In Lassaigne's test,the covalent organic molecules are transformed into ionic compounds.
Statement $II :$ The sodium fusion extract of an organic compound having $N$ and $S$ gives prussian blue colour with $FeSO_4$ and $FeCl_3$.
In the light of the above statements,choose the correct answer from the options given below.
Statement $I :$ In Lassaigne's test,the covalent organic molecules are transformed into ionic compounds.
Statement $II :$ The sodium fusion extract of an organic compound having $N$ and $S$ gives prussian blue colour with $FeSO_4$ and $FeCl_3$.
In the light of the above statements,choose the correct answer from the options given below.
DifficultJEE MAIN 2025
View SolutionWhich compound is responsible for the formation of a blue precipitate when ferric ions react with a Lassaigne's extract or potassium ferrocyanide solution?
Medium
View SolutionMatch the compounds in Column $I$ with their characteristic test$(s)$ reaction$(s)$ given in Column $II$.
Column $I$ Column $II$ $A. H_2N-NH_3^+Cl^-$ $p. \text{Sodium fusion extract of the compound gives Prussian blue colour with } FeSO_4$ $B. HO-C_6H_4-CH(NH_3^+)COOH \text{ (with } I^- \text{ counterion)}$ $q. \text{Gives positive } FeCl_3 \text{ test}$ $C. HO-C_6H_4-NH_3^+Cl^-$ $r. \text{Gives white precipitate with } AgNO_3$ $D. (NO_2)_2C_6H_3-NH-NH_3^+Br^-$ $s. \text{Reacts with aldehydes to form the corresponding hydrazone derivative}$
| Column $I$ | Column $II$ |
|---|---|
| $A. H_2N-NH_3^+Cl^-$ | $p. \text{Sodium fusion extract of the compound gives Prussian blue colour with } FeSO_4$ |
| $B. HO-C_6H_4-CH(NH_3^+)COOH \text{ (with } I^- \text{ counterion)}$ | $q. \text{Gives positive } FeCl_3 \text{ test}$ |
| $C. HO-C_6H_4-NH_3^+Cl^-$ | $r. \text{Gives white precipitate with } AgNO_3$ |
| $D. (NO_2)_2C_6H_3-NH-NH_3^+Br^-$ | $s. \text{Reacts with aldehydes to form the corresponding hydrazone derivative}$ |
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