Inorganic and Applied Chemistry

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Inorganic and Applied Chemistry

which is the subject for the following section. The advantage of coating the steel with zinc is that zinc does

not form as oxide layer.

Zinc is easier to oxidised than iron which may be seen by the comparison of the equations below:

Fe(s)  Fe2+(aq) + 2 e- ,^0 = 0.44 volt

Zn(s)  Zn2+(aq) + 2 e- ,^0 = 0.76 volt

This means that zinc sacrifices itself for the sake of iron meaning that the zinc atoms will be oxidised prior

to the iron atoms thereby expanding the life time of the steel.

6.7 Electrolysis

We have seen previously how a galvanic cell may produce current from a chemical reaction. Similarly we

shall see in this section how the opposite reaction may be used to make a chemical reaction occur. Such a

process is called electrolysis which involves the addition of current in order to make the chemical reaction

occur having otherwise a negative cell potential. This means that the reaction will not take place

spontaneously. We looked briefly into this principles in the example with the lead battery earlier in this

chapter but in this section we will go deeper into the phenomenon of electrolysis.

In order to illustrate the difference between a galvanic cell and an electrolytic cell we will start with the

galvanic cell in the figure below:

Electrochemistry

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