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Question
Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation :
2NaOH + CuSO4 → Na2SO4 + Cu (OH)2 ↓
(i) What mass of copper hydroxide is precipitated by using 200 gm of sodium hydroxide?
[H = 1, O = 16, Na = 23, S = 32, Cu = 64]
(ii) What is the colour of the precipitate formed?
Solution
The Given equation is
2NaOH + CuSO4 → Na2SO4 + Cu(OH)2 ↓
(i) Molecular weight of NaOH , Sodium hydroxide = 23 + 16 + 1 = 40
Molecular weight of Cu(OH)2 ,
Copper hydroxide = 64 + 16 + 1 + 16 + 1 = 98
Now , 40g of NaOH is used to precipitate 98g of Cu(OH)2
Hence , 200g of NaOH will be used to precipitate (98/40)200 g of Cu(OH)2 = 490g of Cu(OH)2 .
So , 490g of copper hydroxide would be prepared using 200g of sodium hydroxide .
(ii) A light blue precipitate of Cu(OH)2 will be formed .
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