Atomistry » Lead » Chemical Properties » Basic Lead Chromate
Atomistry »
  Lead »
    Chemical Properties »
      Basic Lead Chromate »

Basic Lead Chromate, Pb2CrO5

Basic Lead Chromate, Pb2CrO5, PbCrO4.PbO, or 2PbO.CrO3, is formed as a red powder by the action of cold caustic soda solution on the normal chromate. It is also produced by mixing together lead chromate and oxide in presence of water, and is known commercially by various names: chrome red, orange chrome, Derby red, Chinese red, according to its depth of colour. It is converted by acetic acid into the normal salt, and the two salts are in equilibrium in contact with an aqueous solution of 2×10-5 molecules CrO3 per litre at 25° C. Mixtures of the two salts produce shades intermediate between yellow and red; such mixtures are known commercially.

The basic salt Pb3Cr2O9 occurs in dark red hexagonal prisms of a density of 5.75 as the mineral phcenicite or phcenicochroite. This compound may be prepared artificially by allowing solutions of lead nitrate and potassium chromate to mix by diffusion, by exposing a solution of lead chromate in caustic potash to the air for several months, or by immersing galena in potassium dichromate solution for six months. This last process, which was carried out by Meunier, probably nearly reproduces the conditions by which the mineral is naturally produced.

Lead Chromate Double Salts

Double salts of lead chromate with alkali chromates have been obtained. The potassium salt K2CrO4.PbCrO4 or K2Pb(CrO4)2 is formed as a yellow amorphous precipitate when 50 c.c. of a saturated solution of potassium chromate is mixed with 10 c.c. of saturated lead acetate solution. The ammonium salt (NH4)2Pb(CrO4)2 is prepared similarly, and both salts are decomposed into their components by water.

Last articles

Zn in 8WB0
Zn in 8WAX
Zn in 8WAU
Zn in 8WAZ
Zn in 8WAY
Zn in 8WAV
Zn in 8WAW
Zn in 8WAT
Zn in 8W7M
Zn in 8WD3
© Copyright 2008-2020 by atomistry.com
Home   |    Site Map   |    Copyright   |    Contact us   |    Privacy