briefly describe how can you distinguish MgCl2 from ZnCl2 solution (please use c
ID: 723584 • Letter: B
Question
briefly describe how can you distinguish MgCl2 from ZnCl2 solution (please use chemical equations)Explanation / Answer
MgCl2 dissociates to give Mg2+ ions and ZnCl2 dissociates to give Zn2+ ions. they can be separately tested by dissolving them in excess hot NaOH solution. For Mg2+ ions, Mg2+ + 2OH- --------------> Mg(OH)2 this Mg(OH)2 is a white gelatinous ppt which doesn't dissolve even upon addition of excess NaOH For Zn2+ ions initially when Zn2+ is mixed with NaOH Zn(OH)2 precipitates out as per reaction: Zn2+ + 2OH- -----------> Zn(OH)2 (ppt) but when excess NaOH is added, the white ppt dissolves due to formation os soluble complex [Zn(OH)4]2- as per reaction Zn(OH)2 + 2OH- ------------> [Zn(OH)4]2- (soluble) so the key is that when you add excess warm NaOH to both solutions the test tube containing Mg2+ ions will form white ppt which doesnot dissolve upon addition of more NaOH while in the test tube containing Zn2+ ions a white ppt will form which will dissolve upon addition of excess NaOH Using this test these compounds can be distinguished. The solution is entirely correct.. don't worry !! :D
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