Page 18 - Curriculum Visions Dynamic Book

Lead oxides
Lead oxides produce a variety of colours. For example, the most important oxide of lead (called litharge) is an orange substance used in a wide variety of applications. A mixture of litharge and red lead is used as the active coating on the plates of all lead-acid batteries (see page 28). It can be used in glass-making to produce glass that will prevent the penetration of X-rays and other radioactive sources.
The distinctive colour of litharge is used in pottery glazes and enamels and as a toughener in rubber. Made into chrome yellow, it is incorporated into some paints.
Lead oxide is also important when dissolved in sodium hydroxide, where it acts to break up some sulphur compounds in petroleum refineries.
Red lead is used in some paints designed to prevent iron and steel from corroding (see page 24).
 Lead oxides make a variety of colours. Massicot is a yellow form of lead monoxide (lead II oxide or PbO). Lead monoxide is one of the most widely used and commercially important metallic compounds. The bright orange-red powder is known as “red lead” (Pb3O4), whereas the darkest powder is lead dioxide (lead IV oxide, PbO2).
EQUATION: Oxidation of lead
Lead + oxygen ➪ lead monoxide (litharge) 2Pb(s) + O2(g) ➪ 2PbO(s)
Red lead
Red lead is an example of a mixed oxide. Although
its formula is Pb3O4, it behaves chemically as though
it were a mixture of lead monoxide (lead II oxide, PbO) and lead dioxide (lead IV oxide, PbO2). When it is heated, it decomposes to lead monoxide and releases oxygen.
EQUATION: Heating red lead to release oxygen
Red lead ➪ lead monoxide + oxygen 2Pb3O4(s) ➪ 6PbO(s) + O2(g)
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