Electrolysis of salts
Strengthen
CC10b.3
Class
Name
1
Date
−
2+
Molten lead bromide contains lead ions, Pb , and bromide ions, Br . It is electrolysed using graphite
electrodes.
a
Graphite electrodes are used because they are inert. Give the meaning of the word ‘inert’.
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b
Give the name of the electrode that attracts the lead ions. ____________________________________
c
Explain how the lead ions change into lead atoms during the electrolysis.
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d
Give the name of the electrode that attracts the bromide ions. ________________________________
e
Explain how the bromide ions change into bromine molecules during the electrolysis.
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S1 Explain the formation of zinc and chlorine during the electrolysis of molten zinc chloride.
S2 Predict the product formed at each electrode during the electrolysis of molten magnesium bromide.
Justify your answers.
2
Sodium chloride solution is electrolysed using graphite electrodes.
Chlorine forms at the positive electrode and hydrogen forms at
the negative electrode.
a
+
−
Explain why there are H and OH ions in the electrolyte.
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b
Explain how chloride ions change into chlorine molecules at
the positive electrode.
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c
Describe a test to identify the gas as chlorine.
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d
Give a reason why hydrogen forms at the negative electrode
instead of sodium.
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e
Explain how hydrogen ions change into hydrogen molecules at the negative electrode.
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f
Give the name and formula of the compound left in the solution at the end of the electrolysis.
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g
State how the electrolyte would need to be changed to produce sodium at the negative electrode.
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