The sodium fusion test, or Lassaigne’s test, is used in elemental analysis for the qualitative determination of the presence of foreign elements, namely halogens. A method of testing for the presence of a halogen, nitrogen, or sulphur in an organic compound. A sample is heated in a test tube with a pellet of sodium. The hot. A drop of ferric chloride is added to this solution. A prussian-blue precipitate of ferric ferrocyanide, Fe4[Fe(CN)6]3 is formed. The formation of the prussian blue.

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Mass of silver salt taken. From the amount of barium sulphate, percentage of sulphur can be calculated. Show Summary Details Overview Lassaigne’s test.


The solution is allowed to stand for a few hours until it becomes colourless or pale yellow. These extra elements are usually detected by Lassaigne’s Test that was developed by the French Chemist J. Lead acetate test Sodium sulphide formed during the preparation of Lassaigne’s extract reacts with lead acetate to yield lead sulphide as black precipitate. A small amount of the acid with two parts of absolute ethanol and one pare of concentrated sulphuric acid is warmed for 2 minutes. Write down the symbols of the various elements side by side with the above numbers at the lower right corner of each.

Let B represents one molecule of the base. Don’t have an account? A clear solution in NaOH solution which on acidification gives an insoluble material indicates primary amine. Contraction on explosion and cooling. The test teat heating the sample strongly with clean sodium metal, “fusing” it with the sample.


Lassaigne Method | Determination of Molecular Mass-Askiitians

Hydrogen is also present in most of the organic compounds, but there are few exceptions, such as: August Click [show] for important translation instructions. If possible, verify the text with references provided in lsasaigne foreign-language article. Sulphide ions are readily identified using sodium nitroprusside.

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Detection of Elements: Lassaigne’s Test (Theory) : Class 11 : Chemistry : Amrita Online Lab

This method is, however, not applicable to compounds containing nitrogen in the ring e. Dibutyl Ether and Passaigne It is then reduced to NTP conditions. Divide the percentage of each element lassalgne its atomic mass. The test is extremely delicate and will often detect traces of primary amines in secondary and tertiary amines.

Students understand the chemical reactions and their balanced equations that takes place during each test. The molecular mass of the compound can be calculated from the following mathematical relationships:.

Exact name of German article]]; gest its history for attribution. Ammonia solution is added drop by drop until the silver oxide is just dissolved. Fusion solution is acidified with dil. When an organic compound containing sulphur is heated with fuming nitric acid, sulphur is oxidised to sulphuric acid.

Platinichloride method for bases: If a colourless solution is obtained which gives an immediate and sustained positive test with starch indicate paper when only a little sodium nitrite solution has been added the compound is a tertiary aliphatic amine. If the precipitate is white and readily soluble in ammonia solution, chlorine is present; if it is pale yellow and difficulty soluble, bromine is present; if it yellow and insoluble, then iodine and bromine may be confirmed by the following test.


Mass of metallic silver. Both phenol and carboxylic acid turns moist blue litmus paper to red put as phenol gives negative result with NaHCO 3 the above mentioned test is used for tezt carboxylic acids from phenols.

Chemical classification of the amine function: The solution is then filtered and the halide is precipitated with silver nitrate solution. If chlorine is present, a white curdy precipitate soluble in ammonium hydroxide solution is formed. Soluble in water but insoluble in ether. Retrieved from ” https: Select Grade 6 7 8 9 10 11 12 12th pass. This gives the simplest ratio of the various elements present. If the compound is sparingly soluble in water a hot saturated aqueous solution is prepare and filtered.

Occasionally the precipitate is oily at first but this becomes crystalline upon standing. Sodium bicarbonate NaHCO 3 to the 1 ml of the sample a lassaitne of effervescence lassxigne the presence of carboxylic group. For more guidance, see Wikipedia: The “fused” sample is plunged into water, and the usual qualitative tests are performed on the resultant solution for the respective possible constituents. This test is based in the appearance of effervescence due to liberation of hydrogen gas when the alcohol is reacted with active metals like sodium.

Cyanide ion and hence nitrogen ion in the sample, may be detected by the Prussian blue test.

Not containing N or S soluble in conc.