CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 6
Name
Date
6A: Electrochemistry
1 What is electrolysis?
Using __ __ __ __ __ __ __ __ __ __ __ to sp__ __ __ a substance into its __ __ __ __ __ __ __ __ .
2 Explain the conditions required for electrolysis to work.
Electrolysis works when the electrolyte is m__ __ __ __ __ or __ __ __ __ __ __ __ __ __ in water.
This allows the __ __ __ __ to move freely and carry the __ __ __ __ __ __ .
3 Label the electrolytic cell in Figure 6.1 with the following key words.
anode
cathode
electrolyte power supply
Figure 6.1
4 This question relates to the electrolysis of molten compounds.
a Complete the following table.
Salt
Anode
Cathode
Potassium bromide
Bromine
Potassium
Aluminium oxide
Barium iodide
Sodium chloride
Sodium
Calcium fluoride
Magnesium oxide
Oxygen
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CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 6
b Look at your completed table from part a. What is the pattern?
__ __ __ __ __ __ __ __ __ __ are formed at the anode. __ __ __ __ __ __ are formed at
the cathode.
5 Calcium can be extracted from molten potassium fluoride.
a Balance the equation to show the electrolysis of KF2.
_____KF à _____K + F2
b Balance the equations of the reactions that occur at both electrodes.
Anode:
____F− à F2 + ____e−
Cathode:
____K+ + ____ à ____K
6 This question relates to the electrolysis of sodium chloride solution.
a What is produced at each electrode when dissolved NaCl is electrolysed?
Remember that dissolved means H+ and OH− ions are also present. NaCl contains a halide
and a metal that is more reactive than hydrogen.
__ __ __ __ __ __ __ __ gas is formed at the anode. __ __ __ __ __ __ __ __ gas is formed at
the cathode.
b Balance the half-equations to show what is formed when dissolved NaCl is electrolysed.
Anode:
2Cl− à Cl2 + ____e−
Cathode:
____H+ + ____e− à H2
7 What are the three general rules for electroplating a metal object with another metal?
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•
•
The object to be electroplated is connected at the __ __ __ __ __ __ __ .
The metal used to electroplate the object is connected at the __ __ __ __ __ .
The __ __ __ __ __ __ __ __ __ __ __ must contain a solution of the salt of the __ __ __ __ __
to be plated on the object.
8 This question relates to the hydrogen fuel cell.
a What is the definition of a hydrogen fuel cell?
A __ __ __ __ (hydrogen gas) is continuously supplied and reacted with __ __ __ __ __ __ gas.
A __ __ __ __ __ __ __ is generated.
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CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 6
b Balance the overall reaction in a hydrogen fuel cell.
____H2 + O2 à ____H2O
c Balance the oxidation and reduction half-equations.
Oxidation:
____H2 à ____H+ + 4e−
Reduction:
O2 + ____H+ + 4e− à ____H2O
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