CHEMISTRY WORKSHEET
FORM 4G ELECTROLYSIS WORKSHEET TERM 3 2010-2011
1.Figure 1 below is a diagram of the apparatus used in the electrolysis of fused sodium bromide.
Figure 1
a)Write the formulae for the ions present in the fused sodium bromide.
b)Write an ionic equation to represent the reaction taking place at the positive and negative electrodes.
c)When the heat source was removed, the crucible cooled and the lamp went out. Explain why the lamp went out when the crucible cooled.
d)At the end of the experiment, the contents in the crucible were shaken out, and water placed in the crucible to wash out the residue. Bubbles of gas were seen.
(i)Suggest a name for the gas.
(ii)Explain the reaction that was probably taking place in the crucible.
(iii)Write a balanced equation to represent the reaction that was probably taking place in the crucible.
2.One of the factors that affects the formation of products during electrolysis is whether the electrode is active or inert. The following circuit was set up to investigate this factor. W and X are carbon electrodes. Y and Z are copper electrodes.
a)Write the formulae of the ions present in copper(II) sulphate solution.
b)What would you expect to observe in Beakers A and B when a current is flowing through the circuit?
c)Identify the cathode in Beaker A and the anode in Beaker B.
d)Write an ionic equation to represent the reaction occurring at the cathode in Beaker A and the anode in Beaker B.
e)Two industrial applications of electrolysis are purification and anodising.
(i) Explain how an impure sample of copper can be purified
3.The circuit in Figure 2 can be used to test if a substance conducts electricity.
a) Complete Table 1 below to indicate the effect of the bulb in Figure 2, when graphite rod is replaced by EACH of the substances in Table 1.
TABLE 1 : EFFECT ON BULB
Substance
Effect on bulb
Lead
Solid lead bromide
Molten lead bromide
Liquid bromine
b)Classify EACH of the substances in
1.Figure 1 below is a diagram of the apparatus used in the electrolysis of fused sodium bromide.
Figure 1
a)Write the formulae for the ions present in the fused sodium bromide.
b)Write an ionic equation to represent the reaction taking place at the positive and negative electrodes.
c)When the heat source was removed, the crucible cooled and the lamp went out. Explain why the lamp went out when the crucible cooled.
d)At the end of the experiment, the contents in the crucible were shaken out, and water placed in the crucible to wash out the residue. Bubbles of gas were seen.
(i)Suggest a name for the gas.
(ii)Explain the reaction that was probably taking place in the crucible.
(iii)Write a balanced equation to represent the reaction that was probably taking place in the crucible.
2.One of the factors that affects the formation of products during electrolysis is whether the electrode is active or inert. The following circuit was set up to investigate this factor. W and X are carbon electrodes. Y and Z are copper electrodes.
a)Write the formulae of the ions present in copper(II) sulphate solution.
b)What would you expect to observe in Beakers A and B when a current is flowing through the circuit?
c)Identify the cathode in Beaker A and the anode in Beaker B.
d)Write an ionic equation to represent the reaction occurring at the cathode in Beaker A and the anode in Beaker B.
e)Two industrial applications of electrolysis are purification and anodising.
(i) Explain how an impure sample of copper can be purified
3.The circuit in Figure 2 can be used to test if a substance conducts electricity.
a) Complete Table 1 below to indicate the effect of the bulb in Figure 2, when graphite rod is replaced by EACH of the substances in Table 1.
TABLE 1 : EFFECT ON BULB
Substance
Effect on bulb
Lead
Solid lead bromide
Molten lead bromide
Liquid bromine
b)Classify EACH of the substances in