Class 11Chemistry3 Organic Chemistry: Purification and CharacterisationChemical analysis of organic compounds
MediumGive the answers for the Lassaigne test:
$(i)$ If nitrogen and sulphur are both present,what observation is observed?
$(ii)$ If bromine is present,what is the observation?
$(iii)$ In the Lassaigne extract,if black precipitates are not obtained upon adding $CH_3COOH$ and lead acetate,what does this indicate?
$(iv)$ What is the reason for adding $FeSO_4$ to the Lassaigne extract?
$(v)$ Why is the Prussian blue colour observed?
$(vi)$ What does the violet colour with sodium nitroprusside in the Lassaigne extract indicate?
$(i)$ If nitrogen and sulphur are both present,what observation is observed?
$(ii)$ If bromine is present,what is the observation?
$(iii)$ In the Lassaigne extract,if black precipitates are not obtained upon adding $CH_3COOH$ and lead acetate,what does this indicate?
$(iv)$ What is the reason for adding $FeSO_4$ to the Lassaigne extract?
$(v)$ Why is the Prussian blue colour observed?
$(vi)$ What does the violet colour with sodium nitroprusside in the Lassaigne extract indicate?
(N/A) $(i)$ $A$ blood-red colour is obtained due to the formation of $[Fe(SCN)]^{2+}$.
$(ii)$ By adding $AgNO_3$,a pale yellow precipitate of $AgBr$ is formed.
$(iii)$ It indicates that sulphur is absent in the organic compound.
$(iv)$ $FeSO_4$ is added to react with $CN^-$ ions to form ferrocyanide ions,which then react with $Fe^{3+}$ ions.
$(v)$ It is due to the formation of ferric ferrocyanide,$Fe_4[Fe(CN)_6]_3$.
$(vi)$ It indicates that sulphur is present in the compound,forming $Na_4[Fe(CN)_5NOS]$.
$(ii)$ By adding $AgNO_3$,a pale yellow precipitate of $AgBr$ is formed.
$(iii)$ It indicates that sulphur is absent in the organic compound.
$(iv)$ $FeSO_4$ is added to react with $CN^-$ ions to form ferrocyanide ions,which then react with $Fe^{3+}$ ions.
$(v)$ It is due to the formation of ferric ferrocyanide,$Fe_4[Fe(CN)_6]_3$.
$(vi)$ It indicates that sulphur is present in the compound,forming $Na_4[Fe(CN)_5NOS]$.
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Similar Questions
In a Lassaigne's test for sulphur in an organic compound,the purple colour formed with sodium nitroprusside solution is due to the formation of:
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View SolutionBeilstein test is used for the detection of which one of the following elements?
Statement $I$: Nitrogen in pyridine cannot be estimated by Kjeldahl’s method. Statement $II$: Nitrogen in pyridine changes to ammonium sulphate when heated with conc. $H_2SO_4$ in Kjeldahl’s method. Read the above given statements and choose the correct answer from the given options.
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View SolutionWhy is nitric acid $(HNO_3)$ added to sodium extract before adding silver nitrate $(AgNO_3)$ for testing halogens?
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View SolutionMatch column $-I$ and column $-II$ with the correct relation:
Column $-I$ Column $-II$ $(i).$ Lassaigne's test $(a).$ By sodium peroxide $(ii).$ Test for nitrogen $(b).$ Acidify with acetic acid $(iii).$ Test for sulphur $(c).$ Acidify with conc. sulphuric acid $(iv).$ Test for phosphorus $(d).$ Fusion with sodium
| Column $-I$ | Column $-II$ |
|---|---|
| $(i).$ Lassaigne's test | $(a).$ By sodium peroxide |
| $(ii).$ Test for nitrogen | $(b).$ Acidify with acetic acid |
| $(iii).$ Test for sulphur | $(c).$ Acidify with conc. sulphuric acid |
| $(iv).$ Test for phosphorus | $(d).$ Fusion with sodium |
Easy
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