reaction (CHEM)

2009-01-19 7:44 am

write equation and observation of following reaction
1.add ammonia solution to aluminium nitrate solution
2.add dilute sodium hydroxide solution to zinc sulphate solution

回答 (1)

老爺子

2009-01-19 10:02 pm

✔ 最佳答案

1.
A white precipitate is formed.
NH3(aq) + H2O(l) = NH4+(aq) + OH-(aq)
('=' represents double arrows for reversible reaction)
Al3+(aq) + 3OH-(aq) → Al(OH)3(s)
or: Al(NO3)3(aq) + 3NH3(aq) + 3H2O(l) → Al(OH)3(s) + 3NH4NO3(aq)

2.
When sodium hydroxide solution is added to zinc sulphate solution, a white precipitate is formed.
Zn2+(aq) + 2OH-(aq) → Zn(OH)2(s)
or: ZnSO4(aq) + 2NaOH(aq) → Zn(OH)2(s) + Na2SO4(aq)
When excess sodium hydroxide is added to the reaction mixture, the precipitate dissolves to give a colourless solution.
Zn(OH)2(s) + 2OH-(aq) → [Zn(OH)4]2-(aq)
or: Zn(OH)2(s) + 2NaOH(aq) → Na2[Zn(OH)4](aq)
=

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