CHEMISTRY · Single correct · GCSE · Chemistry · Chemical Analysis · Chemical Analysis
Problem
## PASSAGE 25
(i) A white solid mixture of two salts containing a common cation is insoluble in water. It dissolves in dilute HCl producing some gases (with effervescence) that turn an acidified dichromate solution green. After the gases are passed through the acidified dichromate solution, the emerging gas turns baryta water milky.
(ii) On treatment with dilute HNO3 , the white solid gives a solution which does not directly give a precipitate with a BaCl2 solution but gives a white precipitate when warmed with H2O2 and then treated with a BaCl2 solution.
(iii) The solution of the mixture in dilute HCl, when treated with NH4Cl , NH4OH and an Na2HPO4 solution, gives a white precipitate.
The white precipitate obtained in (iii) consists of:
(1) Ba3(PO4)2
(2) Sr3(PO4)2
(3) Ca3(PO4)2
(4) MgNH4PO4⋅6H2O