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

Experiment 19: IDENTIFYING THE Ca++ 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
• (NH₄)₂CO₃
• (NH₄)₂CO₄
• K₄[Fe(CN)₆

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.	No any ppt. was formed	Presence 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 IIIA metal ions

2. Confirmatory test for group IV metal ion (Sr⁺⁺, Ca⁺⁺, Ba⁺⁺):

Experiment	Observation	Inference
1. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of K2CrO4 solution were added to it.	No any ppt. was formed.	Presence of Ca++

Test of Ca⁺⁺ ion

Experiment	Observation	Inference
1. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of (NH4)2CO3 solution were added to it.	White ppt. was formed that dissolved in acetic acid and dil. HCl with effervescence.	Presence of Ca++
2. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of (NH4)2C2O4 solution were added to it.	White ppt. was formed that didn’t dissolve in acetic acid but dissolved in dil. HCl.	Presence of Ca++
3. 2 ml of the original solution was taken in a clean and dry test tube and a few drops of K4[Fe(CN)6 solution was added to it.	White ppt. was formed	Presence of Ca++

Reactions involved:

RESULT

Hence, the sample was identified as Ca⁺⁺ 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.