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known solution test solution added HC1 NaOH observations Pb(NO3)2 A white precip

ID: 694706 • Letter: K

Question

known solution test solution added HC1 NaOH observations Pb(NO3)2 A white precipitate formed. The precipitate dissolved upon addition of more HCI solution A white precipitate formed. Pb(NO3)2 Pb(NO3)2-NaOH solution NH3 Cu(NO3)2 Cu(NO3)2 Cu(NOs)2-NaOH solution NHs Ni(NO3)2 Nag prcpae No reaction A blue precipitate formed. The precipitate dissolved, producing a deep blue solution. No reaction A white precipitate formed The precipitate dissolved, producing a violet solution. HC1 NaOH HCl NaOH Ni(NO3)2 Ni(NOs)2-NaOH solution NH3 (33) (32) n no reoCic irhe reaction mixture

Explanation / Answer

Answer:

2) as we know the Cu+2 does not react with HCl and Pb+2 react with HCl and give a positive test for Pb+2 that means Pb+2 is a presence in mixture, so firstly, we add HCl test solution in a mixture of Pb+2 and Cu+2 which will give a white precipitate, i.e. positive test for Pb+2.

then we add NH3 test solution because it does not affect white precipitate and it reacts with Cu+2, produces a deep blue color precipitate.

3) firstly, we add HCl test solution which precipitates Pb+2 and gives white precipitate, then we add NH3 test solution which gives a positive test for Ni+2 (producing a violet solution) and as we know NH3 does not affect the white precipitate which forms from reaction of Pb+2 with HCl, so we can use NH3 test solution to identify the presence of Ni+2 in given mixture.

if we add NH3 test solution before HCl then it will precipitate Pb+2 in given mixture and give a white precipitate.

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