Lead sulphide

If the normal carbonate is used, the basic carbonate or white lead, Pb(OH),. 2PbCO,. is precipitated. The basic carbonate was used extensively as a base in paints but is now less common, having been largely replaced by either titanium dioxide or zinc oxide. Paints made with white lead are not only poisonous but blacken in urban atmospheres due to the formation of lead sulphide and it is hardly surprising that their use is declining. 

Lead(II) sulphide is oxidised to lead(II) sulphate this reaction has been used in the restoration of old pictures where the white lead pigment has become blackened by conversion to lead sulphide due to hydrogen sulphide in urban air ... 

The use of lead nitrate in place of silver nitrate is to be avoided, for the precipitated lead sulphide occludes most of the free acid. 

Removal of sulphur as sodium sulphide. Dissolve about 0 i g. of c> stine in a few ml. of 10% NaOH solution. Add a few drops of lead acetate solution and boil for 1 minute. The solution darkens owing to the formation of lead sulphide. 

Sulphur, as sulphide ion, is detected by precipitation as black lead sulphide with lead acetate solution and acetic acid or with sodium plumbite solution (an alkaLine solution of lead acetate). Halogens are detected as the characteristic silver halides by the addition of silver nitrate solution and dilute nitric acid the interfering influence of sulphide and cyanide ions in the latter tests are discussed under the individual elements. 

Prepare a solution of sodium plumbite by adding 10 per cent, sodium hydroxide solution to a few drops of about N lead acetate solution until the white precipitate of lead hydroxide initially formed just redissolves to a clear solution. Add 1 ml. of the fusion solution the presence of sulphiu- is indicated by a black precipitate of lead sulphide. 

Acidify 2 ml. of the fusion solution with dilute acetic acid, and add a few drops of lead acetate solution. A black precipitate of lead sulphide indicates the presence of sulphur. 

E. H. Pudey, "Lead Sulphide, Selenide and TeUuride," ia C. A. Hogarth, ed.. Materials Used in Semiconductor Devices, Wiley-Interscience, New York, 1965. 

Lead The production of lead from lead sulphide minerals, principally galena, PbS, is considerably more complicated than the production of zinc because tire roasting of the sulphide to prepare the oxide for reduction produces PbO which is a relatively volatile oxide, and therefore the temperature of roasting is limited. The products of roasting also contain unoxidized galena as well as die oxide, some lead basic sulphate, and impurities such as zinc, iron, arsenic and antimony. 

In the classical Newnham hearth process, the basic sulphate PbS04-2Pb0 reacts with lead sulphide, probably in tire vapour phase, to form lead acording to the reaction... 

Paint Leaded paint blackened by formation of lead sulphide... 

Patches of conductive lead sulphide can be formed on lead in the presence of sewage. This can result in the flow of a large corrosion current . Sulphate-reducing bacteria in soils can produce metal sulphides and H2S, which results in the formation of deep pits containing a black mass of lead sulphide . Other micro-organisms may also be involved in the corrosion of lead in soil . 

Discussion. For the determination of small amounts of lead (0.005-0.25 mg) advantage is taken of the fact that when a sulphide is added to a solution containing lead ions a brown colour, due to the formation of colloidal lead sulphide, is produced. However, for general use the dithizone method (see Section 6.13) is to be preferred and this will be described. 

Schaiifker B, Ferreira Z, Mozota J (1985) Electrodeposition of lead sulphide. Electrochim Acta 30 677-682... 

Sharon M, Ramaiah KS, Kumar M, Neumann-SpaUart M, Levy-Clement C (1997) Electrodeposition of lead sulphide in acidic medium. J Electroanal Chem 436 49-52... 

Ozone Rubber and elastomers of lead sulphide Cracking, weakening... 

Acharya, H. N Bose, H. N. 1971. A chemical method of preparing photoconducting lead sulphide films. Phys. Stat. Sol. 6(a) K43-K44. 

Theory The offcial test is based on the conversion of traces of lead salts present in the pharmaceutical substances to lead sulphide, which is obtained in colloidal form by the addition of sodium sulphide in an alkaline medium achieved by a fairly high concentration of ammonium acetate. The reaction may be expressed as follows ... 

The brown colour, caused due to colloidal lead sulphide in the test solution is compared with that produced from a known amount of lead. 

Abstract In the beginning, the mixed potential model, which is generally used to explain the adsorption of collectors on the sulphide minerals, is illustrated. And the collector flotation of several kinds of minerals such as copper sulphide minerals, lead sulphide minerals, zinc sulphide minerals and iron sulphide minerals is discussed in the aspect of pulp potential and the nature of hydrophobic entity is concluded from the dependence of flotation on pulp potential. In the following section, the electrochemical phase diagrams for butyl xanthate/water system and chalcocite/oxygen/xanthate system are all demonstrated from which some useful information about the hydrophobic species are obtained. And some instrumental methods including UV analysis, FTIR analysis and XPS analysis can also be used to investigated sulphide mineral-thio-collector sytem. And some examples about that are listed in the last part of this chapter. 

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