It isn't clear from your description of HNO3 was added to the decantate or to the ppt. I assume to the ppt.
Pb(C2O4)(s) ==>Pb^2+(aq) + C2O4^2-(aq)
HNO3 dissolves the ppt because it forms H2C2O4 (oxalic acid).
Experiment
Na2C2O4 is added to Pb(NO3)2.Precipitate forms (I think its PbC2O4). After the liquid above was decanted to another container. Dilute HNO3(aq) was added to it. The decanted cloudy solution cleared up a little but it was kinda cloudy still.
Im not sure how PbC2O4(s) <-->Pb^2+ + C2O4^2- equilibrium will react with dilute HNO3(aq).Can someone explain what's happening? What equilibrium is being disturbed?
3 answers
It was added to the decantate.
I can't figure out why anything was added to the decantate; it contains only NaNO3 plus whatever small amount of PbC2O4 that was allowed to spill over. So adding HNO3 will dissolve any of the small particles of H2C2O4.
2 answers