CHAPTER 4. ELECTROCHEMICAL REACTIONS 4.1
(c) SO 2
(d) Cr 2 O^27 −More practice video solutions or help at http://www.everythingscience.co.za(1.) 01qf (2.) 01qg (3.) 01qh (4.) 01qiIn Grade 11, an experiment was carried out to see what happened whenzinc granules
are added to a solution of copper(II) sulphate. In the experiment, the Cu2+ions from the
copper(II) sulphate solution were reduced to copper metal, which wasthen deposited
in a layer on the zinc granules. The zinc atomswere oxidised to form Zn2+ions in the
solution. The half reactions are as follows:
Cu2+(aq) + 2e−→ Cu(s) (reduction half reaction)
Zn(s)→ Zn2+(aq) + 2e−(oxidation half reaction)The overall redox reaction is:
Cu2+(aq) + Zn→ Cu(s) + Zn2+(aq)There was an increase inthe temperature of the reaction when you carried out this ex-
periment. Is it possible that this heat energy could be converted into electrical energy?
In other words, can weuse a chemical reactionwhere there is an exchange of elec-
trons, to produce electricity? And if this is possible, what would happenif an electrical
current was supplied to cause some type of chemicalreaction to take place?
An electrochemical reaction is a chemical reaction that produces a voltage, and there-
fore a flow of electricalcurrent. An electrochemical reaction can also bethe reverse of
this process, in other words if an electrical current causes a chemical reaction to take
place.
DEFINITION: Electrochemical reaction
If a voltage is caused bya chemical reaction, orif a chemical reaction
is caused by an externalvoltage it is an electrochemical reaction.Electrochemistry is the branch of chemistry that studies theseelectrochemical reac-
tions. In this chapter, wewill be looking more closely at different types ofelectrochem-
ical reactions, and howthese can be used in different ways.