Everyday Life and Chemistry - Essentials of Chemical Education - page 227

8.2.9 Working World: Example “Metal Processing”

Etching chemical “ Fe 3+ type ” (E8.12): For the production of special electronic
components copper-coated plastic plates are used. To produce specific conductor lines
for electric current, the plate is prepared with wax-coated corresponding lines. The rest
of the copper layer is dissolved in special solutions, e.g. an iron(III) chloride solution:

2Fe 3 þ ð Cu 2 þ ð 2Fe 2 þ ð

Cu (s) þ aq Þ! aq Þþ aq Þ RR

8.2.10 Electric Power Supply: Example “Accumulators”

Accumulator “ Pb/PbO 2 type ” (E8.13): Accumulators are able to supply electricity
and to be charged again. The best known is the starter battery in the car; it provides
the electrical energy available to start the engine of the car. In the charged condition
the electrodes are in the form of metallic lead and of red-brown lead oxide, during
electron transfer these electrode materials are changing into lead sulfate:

Pb 2 þ ð 2e RR Minus pole : Pb ð s Þ! PbSO 4 Þþ

4H þ ð 2e ! Pb 2 þ ð Plus pole: PbO 2 ð s Þþ aq Þþ PbSO 4 Þ RR

Minus pole
(cathode)

plus pole
(anode)

minus pole
(anode)

plus pole
(cathode)

charging discharging

Chemical reactions for charging and discharging a lithium-ion accumulator

Accumulator “ Li + ion type ” : For energy supply in computers or mobile phones, the
lithium-ion battery is already common; and also in future electric cars this type of
accumulator should run. The following equations and both pictures for charging (left)
and discharging (right) explain the electron transfer for delivering electric power: [ 16 ]

Li þ þ e RR

Minus pole: LiC 6 ! C 6 ð graphite Þþ

Plus pole: Li þ þ e ! LiCo 2 O 4 þ 2LiCoO 2 þ 2H 2 O RR