Observation based questions - Practical chemistry 2

Questions on Analytical chemistry 

Identification of cations using Ammonium hydroxide and Sodium hydroxide

Identify the cation present in each of the following cases based on the colour of the precipitate formed.

1. A salt solution gives a gelatinous white precipitate with small amount of Ammonium hydroxide, and the precipitate is soluble in excess Ammonium hydroxide.

Ans: Zinc ion

2. A salt solution forms a reddish brown precipitate with Ammonium hydroxide which remains insoluble.

Ans:  Ferric ion

3. This salt solution gives a pale blue precipitate with Ammonium hydroxide, this precipitate turns deep (inky) blue solution in excess Ammonium hydroxide.

Ans: Cupric ion

4. When Ammonium hydroxide is added to this salt solution a dirty green precipitate is formed whih is isoluble in excess Ammonium hydroxide.

Ans: Ferrous ion

5. When this salt solution is treated with Ammonium hydroxide solution a white precipitate is formed and insoluble in excess Ammonium hydroxide.

Ans: Lead ion

6. A salt solution is treated with Sodium hydroxide then it gives a gelatinous white precipitate and that white precipitate disappears when excess Sodium hydroxide is added.

Ans: Zinc ion

7. When Sodium hydroxide solution is added to a salt solution, a pale blue precipitate is formed which remains insoluble in excess Sodium hydroxide.

Ans: Zinc ion

8. Two salt solutions A and B are treated with Sodium hydroxide and A reddish brown precipitate and a dirty green precipitate are formed respectively.

Ans: Solution 'A' contains Ferric ion

Solution 'B' contains Ferrous ion