Industrial Applications of Electrolysis
Objective
lesson 6
chapter 13
You will be able to describe, and explain, how
electrolysis is used in common production
facilities.
A common production method for sodium
hydroxide, hydrogen gas, and chlorine gas, is the
chlor-alkali cell. Here sodium chloride undergoes
electrolysis as shown below.
NaCl electrolysis
Anode (+)
Cathode (-)
Net Reaction
2 NaCl(aq)+2H2O(l) ➔ H2(g)+Cl2(g)+2NaOH (aq)
Down's Cell
Molten (fused) NaCl is used to produce
purified chlorine gas and liquid sodium
metal.
Anode reaction:
Cathode reaction:
Hall-Hèroult Process
Alumina, Al2O3, is dissolved in an industrial carbonlined vat of molten cryolite, Na3AlF6 (sodium
hexafluoroaluminate), called a "cell”
cathode: anode: C + 2O2- ➔ CO + 4e2
Electroplating
The electroplating process is a function of electrolysis
whereby solid metal dissolved in solution bonds and
solidifies on surfaces through the application of electric
current.
The object to be plated is placed at the cathode.
The anode contains the metal that will be plated onto
the cathode. (usually)
The electrolyte contains the ion of metal that will be
plated onto the cathode.
Refining Metals
cathode: pure metal-reduction of Cu2+ to form copper
metal at the cathode.
anode: impure metal-Application of a suitable voltage to
the electrodes causes oxidation of copper metal at the
anode.
The anode dissolves and the pure metal is plated at the
cathode.
The electrolyte consists of an acidic solution of CuSO .
4
This strategy can be used because copper is both
oxidized and reduced more readily than water.
Assignment
Read Section 13.3 of your textbook.
Do questions 7 and 8 on page 508, and
questions 17-20 on page 510