| Lead (Pb) |
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50x – Lead nitrate (99.95% pure) crystals resting on glass slide.
The pinkish hue is due to reflected lighting.
50x – The above Lead nitrate crystals in 1 drop HNO3 & 1 drop H2O that has become a super-saturated solution forming a variety of typical and translucent Pb nitrate crystals.
50x – The same solution of super saturated Lead Nitrate, but on/in a different position on glass slide.
50x – PbCl (Lead Chloride) crystal growth, displaying the typical feather appearance.
These transparent to translucent crystals were generated rather quickly when a single NaCl (sodium chloride or table salt) was introduced into the Lead Nitrate solution.
Various forms of these Lead Chloride crystals will form depending upon how concentrated or dilute the solution is, but, usually feathers will manifest.
50x – In a duplicate batch of Lead nitrate a crystal of potassium dichromate was added to the pregnant Lead Nitrate solution, which produced an abundance of these Lead Chromate orange semi-transparent crystals.
50x – The same Lead nitrate solution as the preceding image but in a different location on glass slide, which has formed larger Lead Chromate crystals.
50x – In another Lead nitrate solution (1 drop HNO3 + 1 drop H2O + about same quantity of the Lead Nitrate crystals) was placed a single crystal of KI which formed these zillions of Lead Iodide crystals.
40x – A toothpick tip was dipped in the 1st concentrated Lead nitrate solution and ignited. Very little evidence of metal.
40x – The previous toothpick was ignited again, which produced essentially nothing but very fine burnt wood fibers that have some metal contamination.
This type of toothpick results usually indicates not enough metal in solution, or the metal will not reduce by this means.
If lead is in solution and there is enough it will reduce to form molten beads that seem to run following the hottest part of the burning toothpick tip, as can partially be seen in next image.
40x – The previous toothpick was ignited again, which produced essentially nothing but very fine burnt wood fibers that have some metal contamination.
This type of toothpick results usually indicates not enough metal in solution, or the metal will not reduce by this means.
If lead is in solution and there is enough it will reduce to form molten beads that seem to run following the hottest part of the burning toothpick tip, as can partially be seen in next image.
40x – Same toothpick as the previous image, but it was reignited allowing more small Lead beads to accumulate.
40x – The same toothpick as previous that has been ignited again, which illustrates the tine molten metal Lead beads running away from the red hot tip.
It is common for some of the lead to oxidize forming a red or yellow oxide, which will become more pronounced when other metals are present.
Note: lead fumes when melting the metal or hot vapors rising from a glass slide often will cause a sweet taste in the mouth.
Pb (Lead) + Bi (Bismuth)
10x – The metals 99.95% Pb & 99.9+% Bi were fused with Mapp gas hand-held torch on this plaster tablet.
Not a lot of heat was required to blend these 2 metals.
It is rather obvious that these two metals in roughly the same quantities don’t like being shinny.
40x in two drops of H2O prior to adding a drop of concentrated HNO3.
40x – The bead is in 2 drops H2O & 1 drop HNO3
Quick, vigorous acid attack and this orangish-brown coating formed very fast.
50x – The brownish-orange colored grunge (oxide?) falling off the Pb+Bi bead in the nitric acid solution.
Minor digestion occurring.
Heating of the solution seems to be necessary to cause the acidic solution to attack the metal bead.
Lead alone usually requires 3 drops of water to 1 drop of HNO3 to avoid surface pacification of Lead Nitrate crystals, but even this bead required additional water to avoid Lead nitrate crystals sealing (surface pacification) the bead surface.
70x – Very small black blebs slowly being exposed within/on the bead surface.
Heated the solution with cigarette lighter flame and these blacks dissolved.
Based upon many previous microchems I suspect that these black forms are some kind of form of Bismuth, perhaps an oxide.
40x – A white crystalline coating forming on the bead after a little heat was added. This surface pacification is the result of the Lead nitrate crystals, which have also fell off and can be seen, but not in focus resting on glass slide.
Heat or more water will usually quickly dissolve these white semi-translucent crystals.
There is a slight amount of pinkish coloration on top of the metal bead, likely due to Bismuth, which often transmits a pink color, particularly when minor amounts are alloyed with silver.
With the addition of more heat the solution is gradually becoming dry which is forming super-saturated crystal growth at perimeter of solution as seen in next image.
After another drop of water was added to dissolve the surface nitrates, the next image shows the beads metal crystal structure.
50x – The crystal grain boundaries of the two metals in this format become apparent when more water is added to remove all surface encrustation of nitrates.
The reddish coloration is due to reflecting lighting.
50x – Solution becoming super saturated allowing the crystal formation to the right in mage. These are not typical Pb, for they are too small and narrow, so perhaps a combination of both metals as nitrates.
The gelatinous formation to the left is next to the bead where the Lead nitrate crystals were, but have changed their appearance.
The addition of 1 drop of water and a little heat completely dissolves everything except the original orange-brown grunge (Bi Oxide?).
50x – A different area of the solution that is becoming super-saturated and thus forming what appears to me as being a combined Pb + Bi semi-transparent crystal nitrates.
50x – A single NaCl (sodium chloride in center of image) crystal added to solution forming what appears to be mostly, if not all PbCl, but there are no typical PbCl feathers.
What the other white crystals are that are very close to the NaCl crystal I don’t know, except perhaps a contaminated PbCl?
50x – A single crystal of K2Cr2O7 (potassium dichromate) added to the solution of pregnant nitrate solution quickly produced these orange crystals that appear to be a mixture of Pb & Bi.
The next image is after 10 minutes had elapsed.
70x – The K2Cr2O7 crystal that is slowly precipitating these orange crystals that are not typical Lead Chromates.
50x – A single crystal of KI (Potassium Iodide) instantly precipitated these zillions of yellow Lead Iodide crystals in the same solution that was diluted with 3 more drops of water to avoid the Iodine being reduced.
The needle bunches are often associated with this type of precipitation when Lead nitrate is present.
These needles are actually white and semi-transparent, but reflected lighting is causing color distortions.
40x – A toothpick tip was dipped in the original saturated Pb+Bi nitrate solution. This toothpick upon ignition produced only a few tiny metal beads that became grunge when the burning ceased as the next image illustrates.
40x – Focused upon the semi-metallic appearing grunge after burning had ceased.
The spheroids on the partially burnt toothpick is some of the yellow-orange grunge that was partially metal.
A few tiny beads of metal remained.
I would say that what Lead was reduced, but contaminated with the Bismuth oxidized and become what I am calling grunge
The conclusion I find myself is that KI and NaCl produce ample evidence of Pb, but not of Bi. The K2Cr2O7 suggests serious contamination of the two metals. Consequently none of the 3 reagents used to cause precipitation definitely illustrates the presence of Bi. So, at least another reagent chemical is required to prove the presence of Bi.