7. To analyse the acidic and basic radical in the given salt.(NH4Cl-)

Aim:- To analyse the acidic and basic radical in the given salt.

Physical Examination of Test:-

Colour – White

Smell – Ammonical

Appearance – Amorphous

Dry Heating Test:-

Procedure	Observation	Inference
Take a small amount of salt in dry test take and heat.	Gas evolved with ammonical smell.	NH4+ may be present.
	Pungent smell gas with ammonia.	Cl- may be present.

Identification of Acid Radicals (ANION):-

Dilute Sulfuric Acid tests:-

No reaction

Concentrated Sulfuric Acid test:-

Procedure	Observation	Inference
Take a small quantity of salt with concentrated sulfuric acid (2-3 ml) in a test tube.	Colourless gas with pungent smell. The gas gives white fumes with aqueous ammonia(NH4OH) and white precipitate with AgNO3.	Gas evolved = HCl Possible Radical = Cl-

Confirmation of Acid Radical by wet tests:-

Aqueous solution or water extract: Shake a little of the salt with water. If the salt dissolves, this aqueous solution obtained is used for the wet test of acid radicals and is called ‘Water extract’ or ‘W.E’.

Confirmation of Cl^-

Procedure	Observation	Inference
Take a small portion of aqueous solution and acidity it with HNO3. Boil for some time cool and add silver nitrate to it.	A Curdy white precipitation is formed which is solute in ammonium hydroxide.	Cl­- is present.

Wet test for basic radicals(CATIONS):-

Properties of solution for wet tests of Basic Radicals: If the salt is insoluble in distilled as well as dilute HCl, try to dissolve it in concentrated HCl, first in cold and then on heating. The clear solution thus obtain is labelled as Original Solution(O.S).

Analysis of Group Zero(NH_4­⁺):-

Procedure	Observation	Inference
Salt solution is heated with sodium hydroxide.	Ammonical gas is evoled.	NH4- may be present.
Pass the gas through Nessler’s Reagent.	Brown precipitate is formed	NH4+ is present.

Results:-

Acid Radical: Cl^-

Basic Radical: NH₄^-

Therefore, the salt is NH₄Cl^-.