# State the observation: 1.when crystals of copper sulphate are heated in a test tube 2.Ammonium sulphate is heated with NaOH and the gas liberated is bubble into methyl orange soln. 3.Ammonia gas is passed through copper nitrate solution.

Dear student,

1. Copper sulphate crystal (CuSO4.5H2O ) when heated in a test tube, it loses its water of crystallistion and changes its colour from blue to white.

2. Ammonium sulphate reacts with NaOH to form sodium sulphate, ammonia gas and water.
(NH4)2SO4 + 2NaOH $\to$ Na2SO4 + 2NH3 + 2H2O
Ammonia in water forms ammonium hydroxide( NH4OH), which is basic in nature.
NH3 + H2O  $\to$ NH4OH
This changes the colour of methyl orange indicator from orange to yellow.

3. The blue colour of the copper(II) becomes more intense( or deep blue)  on additon of ammonia gas due to formation of a complex compound.
Cu2+ (aq) + 4 NH3(aq)   $\to$ [Cu(NH3)4] 2+(aq)
blue                                      deep blue
Regards

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1 change in colour

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1. The colour of copper sulphate crystals before heating is blue and turns white after heating.
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3. Inky blue colouration
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