When metal X is treated with NaOH, 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 ). 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.
Answers
Answer:
(a) Green crystals of a substance changed their colour on heating in a closed 5
test tube but regained it after sometime when they were allowed to cool
down. Name the substance and write its formula.
(b) Name the compound whose one formula unit is associated with 10 water
molecules. How is it prepared from sodium chloride? Give equations of
related reactions. Give two uses of the compound.
Explanation:
(a) Green crystals of a substance changed their colour on heating in a closed 5
test tube but regained it after sometime when they were allowed to cool
down. Name the substance and write its formula.
(b) Name the compound whose one formula unit is associated with 10 water
molecules. How is it prepared from sodium chloride? Give equations of
related reactions. Give two uses of the compound.
Answer:
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.
Explanation:
Solution :
The given metal X gives a white precipitate with sodium hydroxide and the 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). <br>
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<br> Now, when dilute hydrochloric acid is added to aluminium hydroxide, aluminium chloride (compound C) is obtained. <br>
<br> 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. <br>