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Question
What do you observe when caustic soda solution is added to the following solution, first a little and then in excess:
ZnSO4
Write a balanced equation for this reaction.
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Solution
\[\ce{\underset{\text{Colourless}}{ZnSO4} + 2NaOH -> \underset{\text{white gelatinous ppt.}}{Zn(OH)2↓} + \underset{\text{Colourless}}{Na2SO4}}\]
In excess of alkali , White gelatinous ppt. of Zn(OH)2 becomes soluble :
\[\ce{Zn(OH)2 + 2NaOH(excess) -> \underset{\text{Sodium Zincate (Colourless)}}{Na2ZnO2 + 2H2O}}\]
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