Class 11 Chemistry - Chapter The p Block Elements NCERT Solutions | When metal X is treated with sodium hydr
When metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of NaOH to give soluble complex (B). Compound (A) is soluble in dilute HCl to form compound (C). The compound (A) when heated strongly gives (D), which is used to extract metal. Identify (X), (A), (B), (C) and (D). Write suitable equations to support their identities.
The given metal X gives a white precipitate with sodium hydroxide and this precipitate dissolves in excess of sodium hydroxide. Hence, X must be aluminium.
The white precipitate (compound A) obtained is aluminium hydroxide. The compound B formed when an excess of the base is added is sodium tetrahydroxoaluminate(III).
2Al + 3NaOH → Al (OH)3 ↓ + 3Na+
Al(OH)3 + NaOH → Na+ [Al(OH)4]-
(A)
Now, when dilute hydrochloric acid is added to aluminium hydroxide, aluminium chloride (compound C) is obtained.
Al(OH)3 + 3HCl → AlCl3 + 3H2O
(A) (C)
Also, when compound A is heated strongly, it gives compound D. This compound is used to extract metal X. Aluminium metal is extracted from alumina. Hence, compound D must be alumina.
2Al(OH)3 → Al2O3 + 3H2O
(A) (D)
More Questions From Class 11 Chemistry - Chapter The p Block Elements
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What happens when
(a) Borax is heated strongly,
(b) Boric acid is added to water,
(c) Aluminium is treated with dilute NaOH,
(d) BF3 is reacted with ammonia?
- Q:-
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(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.
(iii) Graphite is used as lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.
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(vi) B2H6 + NH3 →
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A certain salt X, gives the following results.
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Write equations for all the above reactions and identify X, Y and Z.
- Q:-
(a) Classify following oxides as neutral, acidic, basic or amphoteric:
CO, B2O3, SiO2, CO2, Al2O3, PbO2, Tl2O3
(b) Write suitable chemical equations to show their nature.
- Q:-
An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
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