Chemistry
Which of the following is the best reagent to distinguish lead nitrate and zinc nitrate ?
P NaOH solution
Q KOH solution
R NH4OH solution
Only P
Only R
Only Q
Both P and Q
Analytical Chemistry
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Answer
Both P and Q
Reason — On adding NaOH or KOH to lead nitrate, a white precipitate of lead hydroxide [Pb(OH)₂] is formed, which is insoluble in excess NaOH or KOH.
On adding NaOH or KOH to zinc nitrate, a white precipitate of zinc hydroxide [Zn(OH)₂] is formed, which is soluble in excess NaOH or KOH, forming a clear solution.
Even though NH₄OH can separate the two, it is not the most effective reagent because, although it produces a white precipitate with both, lead hydroxide does not dissolve in excess NH₄OH, while zinc hydroxide does.
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Related Questions
A metal which produces hydrogen on reacting with alkali as well as with acid:
- Iron
- Magnesium
- Zinc
- Copper
The salt solution which does not react with ammonium hydroxide is:
- Calcium nitrate
- Zinc nitrate
- Lead nitrate
- Copper nitrate
Assertion (A): Calcium salt solution does not show any change even after adding an excess of ammonia solution to it.
Reason (R): The low concentration of hydroxide ion in ammonium hydroxide solution which are unable to precipitate the hydroxide ions of calcium
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Iron (II) salt solution when reacted with ammonium hydroxide forms a dirty green precipitate.
Reason (R): Iron salts are brown in colour.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.