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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.
Using sodium hydroxide solution, how will you distinguish: Zinc nitrate solution from calcium nitrate solution
Using sodium hydroxide solution, how will you distinguish:
Lead hydroxide from magnesium hydroxide.
Write equation for the reaction that will take place when copper sulphate solution is added to sodium hydroxide solution.
Write the observation, and balanced equation for the following reaction:
Sodium hydroxide is added dropwise to a solution of zinc sulphate, till it is in excess.
A white solid A when heated with sodium hydroxide solution, gives a pungent gas B, which turns red litmus blue. The solid, when dissolved in dilute nitric acid and treated with silver nitrate gives a white precipitate of C which is soluble in an ammonia 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) |
What is observed when hot, concentrated caustic soda solution is added to aluminium? Write a balanced equation.
State one relevant observation for the following:
To the copper nitrate solution, initially, few drops of sodium hydroxide solution is added and then added in excess.
