I produced some PbO2 by dissolving a lead pipe piece in HNO3,then precipitate with NaOH and oxidation with domestic bleach.
The filtered brown power does not disolve in HNO3 and releases Cl2 from HCl, so i think is truly PbO2
Books say to recognize Mn+2, you add the Mn sample to a tube with concentrated (I used 65%) HNO3, some PbO2, heat a little and if Mn+2 is there, a purple color will develop due to MnO4...
No way...I tryed several times and all I get is a brown precipitate of PbO2 in the bottom of the test tube and no colour...I'm sure there is Mn there because i put some MnSO4 there just to test if this technique is true. And nothing happens! What is happening here?
I want this to analyze some stones with black spots, to check if they are Fe or Mn. I mixed some pieces witk KNO3 and NaOH,melt all together, and a sligh green colour developed, but i'm not sure if it is Mn there..