11.28: When metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of to give soluble complex (B). Compound (A) is soluble in dilute 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.
In given information, when X is treated with sodium hydroxide, it gives A (white ppt) and it is soluble in excess of . Thus X must be aluminium. So, the white ppt of A is aluminium hydroxide.
The complex B is soluble in excess of sodium hydroxide So it means it is a sodium tetrahydroxy aluminate(II) complex.
Now, when we add dilute HCl to aluminium hydroxide, it gives the compound C (aluminium chloride).
(A) (C)
And when compound (A) is heated strongly, it gives D and this compound used to extract metal X
(A) (D)