IDENTIFYING THE Mg++ BASIC RADICAL PRESENT IN GIVEN INORGANIC SALT

Experiment 22: IDENTIFYING THE Mg++ BASIC RADICAL PRESENT IN GIVEN INORGANIC SALT

OBJECTIVE:

TO IDENTIFY THE BASIC RADICAL PRESENT IN GIVEN INORGANIC SALT

APPARATUS REQUIRED

• Test tube
• Test tube holder

CHEMICALS REQUIRED

• Dil. HCl
• H₂S
• NH₄OH
• NH₄Cl
• NaOH
• (NH₄)₂CO₃
• Na₂HPO₄

THEORY

Qualitative inorganic analysis is concerned with the detection and identification of radicals present in inorganic salt or a mixture of salts. Inorganic salts are the outcome of the neutralization of acids with base. Each inorganic salt consists of two parts. The part contributed by acid is called acid radical or anion and the part contributed by base is called basic radical or cation. For example, in sodium chloride, which can be obtained by the neutralization of base NaOH with acid HCl, Na⁺ is the basic radical and Cl^– is the acid radical.

PROCEDURE

The original solution was prepared by dissolving the given salt sample in water. The sample was subjected to several tests to detect the basic radical of the salt.

OBSERVATION

1. Preliminary test:

a. State: Solid
b. Odour: Odourless
c. Colour: White
d. Solubility: Soluble in water

Group Separation Table

Experiment	Observation	Inference
1. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of dil. HCl was added to it.	White ppt. was not formed	Absence of Group I metal ions
2. The solution above was passed to the H2S solution.	No any ppt. was formed	Absence of Group II metal ions
3. 2 ml of the original solution was taken in a clean and dry test tube and a double volume of NH4Cl was added and shaked. Then NH4OH solution was added.	No any ppt. was formed	Absence of Group IIIA metal ions
4. The solution above in 3 was warmed and H2S was passed.	Black ppt. was not formed.	Absence of Group IIIB metal ions
5. The solution above in 3 was warmed and H2S were passed.	No any ppt. was formed.	Absence of Group IIIB metal ions
5. 2 ml of the original solution was taken in a clean and dry test tube and NH4Cl and NH4OH solution were added. It was warmed and ammonium carbonate solution was added.	White ppt. was formed	Presence of Group V metal ions

2. Confirmatory test for group V metal ion (Mg⁺⁺):

Experiment	Observation	Inference
1. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of NaOH solution were added to it.	White ppt. was appeared which was soluble in NH4Cl.	Presence of Mg++
2. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of NH4OH solution were added.	White gelatinous ppt. appeared which was soluble in NH4Cl.	Presence of Mg++
3. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of Na2HPO4 solution were added.	White crystalline ppt. appeared which was soluble in acetic acid.	Presence of Mg++

Reactions involved:

RESULT

Hence, the sample was identified as Mg⁺⁺ basic radical.

CONCLUSION

Hence, we can test the basic radicals of a salt by wet ways testing the original solution with several reagents.

PRECAUTION

1. Concentrated solutions should be handled carefully.
2. The colour of the precipitate should be observed carefully.
3. Check whether the original solution is clear and transparent.