What is Lassaigne Test ?
Write down chemical reaction to support your answer.
Share
What is Lassaigne Test ?
Write down chemical reaction to support your answer.
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Your answer is in the attachment
Hope it will help you dear
Have a nice day
Verified answer
Explanation:
Nitrogenn, Sulphur, and halogens present in organic compounds are detected by Lassaigne’s test. Here, a small piece of Na metal is heated in a fusion tube with the organic compound. The principle is that, in doing so, Na converts all the elements present into ionic form.
Na + C + N → NaCN
2Na + S → Na2S
Na + X → NaX ( X= Cl, Br, or I)
Test for Nitrogen
The extract is boiled with FeSO4 and acidified with concentrated H2SO4. The appearance on Prussian blue colour indicates the presence of nitrogen.
The following reactions occur,
Fe2+ + 6CN– → [Fe(CN)6]4-
Fe2+ + H+→ Fe3+ + e–
[Fe(CN)6]4- + 4Fe3+ → Fe4[Fe(CN)6].H2O
Test for Sulphur
The extract is treated with sodium nitroprusside. The appearance of violet colour indicates the presence of sulphur.
The following reaction occurs:
S2- + [Fe(CN)5NO]2- → [Fe(CN)5NOS]4-