Chemistry
Write balanced equations for — (a) Aluminium (b) Zinc — is warmed with NaOH [caustic soda] soln.
Sodium Hydroxide
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Answer
Aluminium
2Al + 2NaOH + 2H2O ⟶ 2NaAlO2 + 3H2Zinc
Zn + 2NaOH ⟶ Na2ZnO2 + H2
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Related Questions
Action of Alkalis — on oxides and hydroxides of certain metals 19. Zinc oxide ZnO + NaOH ⟶ …………… + …………… 20. Zinc hydroxide Zn(OH)2 + NaOH ⟶ …………… + …………… 21. Lead [II] oxide PbO + NaOH ⟶ …………… + …………… 22. Lead hydroxide Pb(OH)2 + NaOH ⟶ …………… + …………… 23. Aluminium oxide Al2O3 + NaOH ⟶ …………… + …………… 24. Aluminium hydroxide Al(OH)3 + KOH ⟶ …………… + …………… Sodium hydroxide solution is added first in a small amount, then in excess to the aqueous salt solutions of:
- copper [II] sulphate
- zinc nitrate
- lead nitrate
- iron [III] sulphate
State in each case :
(i) the colour of the precipitate when NaOH is added in a small quantity;
(ii) the nature of the precipitate [i.e. soluble or insoluble] when NaOH is added in excess.
The questions below refers to the following salt solutions listed A to F:
A: Copper nitrate
B: Iron [II] sulphate
C: Iron [III] chloride
D: Lead nitrate
E: Magnesium sulphate
F: Zinc chloride
(i) Which soln. becomes a deep/inky blue colour when excess of ammonium hydroxide is added to it.
(ii) Which solution gives a white precipitate with excess ammonium hydroxide solution.
From the list of substances given — Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State a solution of the compound which gives a dirty green precipitate with sodium hydroxide.