wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

In lead acetate test of sulphur detection, Lassaigne extract is acidified with ______ and then lead acetate solution is added.

A
Oxalic acid
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
Hydrochloric acid
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
Sulphuric acid
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
Acetic acid
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution

The correct option is D Acetic acid
Lassaigne's Test:
A small piece of a sodium metal is heated gently in a fusion tube till it melts to a shining globule. At this stage, a small amount of substance is added and the tube is heated strongly. The red hot tube is plunged into distilled watr contained in a china dish. The contents are boiled for some time, cooled and then filtered. The filtrate is known as sodium extract or Lassaigne's extract. The extract contains sodium sulphide formed by the reaction between sulphur (present in the compound) and sodium.
2Na+SNa2S
The Lassaigne's extract is divided into two parts and following tests are performed. Lead acetate test: One part of the extract is aciddified with acetic acid and then lead acetate solution is added. Formation of a black precipitate confirms the presence of sulphur in the organic compound.
Na2S+Pb(CH3COO)2PbS+2CH3COONa
Sodium nitroprusside test. A few drops of sodium nitroprusside solution are added to another part of the Lassaigne's extract. The appearance of purple colouration confirms the presence of sulphur:
Na2S+Na2[Fe(CN)5NO]Na4[Fe(CN)5NO.S]

flag
Suggest Corrections
thumbs-up
4
Join BYJU'S Learning Program
Join BYJU'S Learning Program
CrossIcon