chem

chemistry

PbS

black

ag20

white

3

2

5

4

PbCrO4 + 4 NaOH —>

Pb(OH)4{-2} + Na2CrO4 + 2 H2O

Pb{+2} +NaOH —→X

X +NaOH(x’s) ——> Y

Y + O.A.(H2O2/ S2O8) ——→ Z

X= Pb(OH)2

Y= Na2[Pb(OH)4 (colorless and soluble complex)

Z= PbO2 (black)

Pb{+2} +aq.H2S —→ X

X + conc.HNO3 ——> Y

X + conc.HNO3 (long time) ——→ Z

X= PbS (black)

Y= Pb{+2} + S(ppt) + NO(evolved)

Z= PbSO4 (ppt)

PbCrO4 + H+(acidic medium) ——>

Pb{+2} + Cr2O4{-2} (orange red)

PbCrO4 + H+(acidic medium) ——>

$2Pb^{2+} + Cr_2O_7^{2-} + H_2O$ (orange solution)

PbCl2 + KI —→

PbI2​(s)+2KCl(aq) (golden yellow precipitate)

Pb{+2} + 2 CN{-1} —→ X

X + KCN(x’s) ——> Y

X = $Pb(CN)_2$ (white precipitate)

Y = Insoluble in excess $KCN$ (no complex formed)

Solution of PbCl2 + ______ —→ yellow ppt

K2​CrO4​ (yellow ppt —→ PbCrO4​)

X

X +Aqua Regia ——> Y

Y + S{-2}(aq) ——>

X= Hg2S (black) [ppt]

Y= HgCl2

Z= [HgS2]-2