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Question
A student was asked to perform an experiment in the laboratory based on the instructions given:
Observe the picture given below and state one observation for the experiment you would notice on mixing the given solution.
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Solution
Blue precipitate dissolves to form an inky blue/deep blue solution.
Explanation:
The light blue precipitate of copper(II) hydroxide (Cu(OH)2) dissolves in excess of ammonium hydroxide due to the formation of a deep blue complex, tetraamminecopper(II) ([Cu(NH3)4]2+), making it soluble.
RELATED QUESTIONS
Identify the substance underlined, in the following case:
Cation that does not form a precipitate with ammonium hydroxide but forms one with sodium hydroxide.
Name the kind of particles present in sodium hydroxide solution.
Name a yellow monoxide that dissolves in hot and concentrated caustic alkali.
Sodium hydroxide solution is added to solution A. A white precipitate is formed which is soluble in excess sodium hydroxide. Name the metal ion present in A.
Three test tubes contain calcium nitrate solution, zinc nitrate solution and lead nitrate solution.Describe the effect of Adding sodium hydroxide solution to each portion in turn till it is in excess.
Using Sodium hydroxide solution, how would you distinguish: Zinc nitrate solution from calcium nitrate solution.
Sodium hydroxide solution is added first in a small quantity, then in excess to the aqueous salt solutions of copper (II) sulphate, zinc nitrate, lead nitrate, calcium chloride, and iron (III) sulphate. Copy the following table and write the colour of the precipitate in (i) to (v) and the nature of the precipitate (soluble or insoluble) in (vi) to (x).
| Aqueous salt solution | Colour of precipitate when NaOH is added in a small quantity | Nature of precipitate (soluble or insoluble) when NaOH is added in excess |
| Copper (II) sulphate | (i) | (vi) |
| Zinc nitrate | (ii) | (vii) |
| Lead nitrate | (iii) | (viii) |
| Calcium chloride | (iv) | (ix) |
| Iron (III) Sulphate | (v) | (x) |
Distinguish by adding:
Sodium hydroxide solution and ammonium hydroxide solution to lead nitrate solution and zinc nitrate solution.
Distinguish by adding:
Sodium hydroxide solution and ammonium hydroxide solution to Fe(II) salt solution and Fe(III) salt solution.
What is observed when hot, concentrated caustic soda solution is added to zinc? Write a balanced equation.
