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प्रश्न
You are provided with PbCO3, ZnCO3 and CaCO3. How will you identify these cations?
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उत्तर
By use of Ammonium hydroxide we can identify the ions PbCO3, ZnCO3 and CaCO3 as :
(i) \[\ce{PbCO3 + 2NH4OH -> Pb(OH)2 v + 2NH4NO3}\]
Pb(OH)2 forms white precipitate which are insoluble in excess ammonium hydroxide.
(ii) \[\ce{ZnCO3 + NH4OH -> Zn(OH)2 v + 2Na2CO3}\]
Zn(OH)2 forms white gelatinous precipitate which are soluble in excess ammonium hydroxide.
(iii) \[\ce{CaCO3 + NH4OH -> Ca(OH)2 + 2Na2CO3}\]
No precipitation of Ca(OH)2 occurs even with addition of excess of NH4OH. Because the concentration of hydroxide ion from ammonium hydroxide is so low that it cannot precipitate the hydroxide of calcium.
Concept Insight : Some precipitated metallic hydroxides by ammonium hydroxide become soluble hydroxides when treated with excess of ammonium hydroxide due to the formation of a soluble complex salt in the presence of excess of ammonium hydroxide.
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संबंधित प्रश्न
State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions :
1) Copper sulphate solution
2) Zinc sulfate solution.
On adding dilute ammonia solution to a colourless solution of a salt, a white gelatinous precipitate appears. This precipitate however dissolves on addition of excess of ammonia solution. Identify (choose from Na, Al, Zn, Pb, Fe)
Which metal salt solution was used?
How will you distinguish NH4OH solution from NaOH solution?
Name the metal hydroxides which are soluble in ammonium hydroxide solution.
Choose the correct answer from the options given below :
Which salt solution is soluble in excess of NH4OH
Write the observation, and balanced equation for the following reaction:
Ammonium hydroxide is added first in a small quantity, and then in excess, to a solution of copper sulphate.
State what do you observe when ammonium hydroxide to Iron (III) sulphate solution.
Write the observation for the following :
NH4OH is added first in a small quantity and then in excess to a solution of copper sulphate.
Identify the cation in the following case:
Ammonium hydroxide solution when added to Solution B gives a white precipitate which does not dissolve in excess of ammonium hydroxide solution.
Write balanced equation:
Copper sulphate solution with ammonium hydroxide solution.
