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soluble in: coldwater hot water PbCl 2 no yes Mg(OH) 2 no no Na 2 SO 4 yes yes A

ID: 677053 • Letter: S

Question

                               soluble in:
                 coldwater          hot water
PbCl2          no                   yes
Mg(OH)2    no                        no
Na2SO4      yes                      yes

A mixture was known to contain two of the three compounds listed inthe above table. After the mixture of Compounds A and B wasextracted with hot water and filtered, Compound A was obtained byevaporating the filtrate to dryness. Both Compounds A and Bwere insoluble in cold water.

Identify Compounds A and B. Briefly explain your answer.

Explanation / Answer

      Comound A is PbCl2 , Compound B is Mg(OH)2 Since both the compounds in the mixture sre insolublein cold water They may be PbCl2 and Mg(OH)2 . When the mixture is extracted with hot water andfiltered PbCl2 which is soluble in hot water comesin to the filterate, and Mg(OH)2 is the residue . After evaporation of water, PbCl2  which is present inthe filterate is obtained . So the compound A isPbCl2 and the compound B isMg(OH)2