10. To analyse the acidic and basic radical for a given salt.(CaCO3)

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

Physical Appearance:

Colour – White

Smell – Odourless

Appearance – Amorphous

Dry Heating Test:-

Procedure	Observation	Inference
Take a small amount of salt in dry test tube and heat it.	White residue	Ca2+ may be present.

Dilute Sulfuric Acid Test:-

Procedure	Observation	Inference
Take a small amount of salt and make the solution. Add few drops of dilute HCl	Colourless, odourless gas with brisk effervescence which turns lime water milky.	Co32- may be present.

Flame Test:-

Procedure	Observation	Inference
Take a pinch of salt, make a paste by adding dilute HCl to it	Brisk red flame.	Ca2+ may be present.

Confirmation of Acid Radical by Wet Test:-

Aqueous Solution: Shake a little of salt with water, if the salt dissolved, the aqueous solution is obtained is used for wet tests of the acid radical and is called water extract.

Procedure	Observation	Inference
Dilute HCl test: To one portion of the solution add dilute HCl.	Brisk effervescene evolution of colourless and odourless gas turns lime water milky.	Co32- is present.
MgSo4 test: Add Mgso4 to the salt solution.	Formation of white precipitate.	Co32- is present.

Wet Test for Basic Radicals:-

Preparation of solution for wet test of basic radicals: If the salt is insoluble in distilled water as well as dilute HCl, try to dissolve in concentrated Hcl first in cold water and then on heating . The clear solution thus obtained is original solution.

Analysis of Group Zero:-

Procedure	Observation	Inference
The solid is heated with concentrated solution of NaOH	No gas evolved.	Group zero absent.

Analysis of Group 4:-

Procedure	Observation	Inference
In the same Ammonial solution of group 3 pass H2S gas	No precipitate.	Group 4 absent.

Analysis of Group 5:-

To the original solution add 2-3 grams of solid NH₄cl boil, cool and add NH₄OH till the solution smell that of NH₃. Then add Ammonium Oxalate solution. Appearance of white precipitate indicate the presence of 5^th group cation.

Procedure	Observation	Inference
To the 1/3 rd portion of solution add 1-2 ml of ammonium oxalate solution. Add a little NH4OH to it and scratch it sides.	Formation of white precipitate.	Ca2+ is present.

Result:-

Acid Radical – CO₃^2-

Basic Radical – Ca²⁺

Therefore, the salt is CaCO₃.