1.58C: Describe Experiments to Investigate Electrolysis, Using Inert Electrode, of Molten Compounds (Including Lead (II) Bromide) and Aqueous Solutions (Including Sodium, Chloride, Dilute Sulfuric Acid and Copper (II) Sulphate) and to Predict the Products

ELECTROLYSIS: Decomposition of an ionic substance by passing an electric current through it

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ELECTROLYSIS OF LEAD (II) BROMIDE:

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ELECTROLYSIS OF LEAD (II) BROMIDE
Diagram showing the Electrolysis of Lead (II) Bromide
METHOD: Add Lead (II) Bromide into a beaker and heat until molten, allowing ions to be free to move to conduct an electric charge Add two Graphite rods as the electrodes and connect this to a power pack or battery Turn on power pack or battery and allow Electrolysis to occur
REACTION AT ELECTRODES:
SOLUTION	PRODUCT AT POSITIVE ELECTRODE	PRODUCT AT NEGATIVE ELECTRODE
LEAD (II) BROMIDE ( PbBr2 )	Bromine   -   Br2 2Br -     -     2e-     →     Br2	Lead   -   Pb Pb2+     +     2e-     →     Pb

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ELECTROLYSIS OF AQUEOUS SOLUTIONS:

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RULES:

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• Aqueous Solutions will Always have Water ( H2O )

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Positive Electrode

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• Either Oxygen or Non-Metal will be produced E.g Chlorine, Bromine, Nitrogen

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Negative Electrode

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• Either Hydrogen or Metal will be produced
• If Metal is above Hydrogen in Reactivity Series, Hydrogen will be produced
• If Metal is below Hydrogen in Reactivity Series, Metal will be produced

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ELECTROLYSIS OF AQUEOUS SOLUTIONS
Diagram showing the Electrolysis of Aqueous Solutions
METHOD: Add Aqueous Solution into a beaker Add two Graphite rods as the electrodes and connect this to a power pack or battery Turn on power pack or battery and allow Electrolysis to occur
REACTION AT ELECTRODES:
AQUEOUS SOLUTION	PRODUCT AT POSITIVE ELECTRODE	PRODUCT AT NEGATIVE ELECTRODE
SODIUM CHLORIDE ( NaCl )	Chlorine   -   Cl 2Cl-  -  2e-  →  Cl2	Hydrogen    -   H2 2H2O  +  2e-  →  H2  +  2OH-
DILUTE SULFURIC ACID ( H2SO4 )	Oxygen   -   O2 2H2O  -  4e-  →  O2  +  4H+	Hydrogen   -    H2 2H+  +  2e-  →  H2
COPPER (II) SULFATE ( CuSO4 )	Oxygen   -   O2 2H2O  -  4e-  →  O2  +  4H+	Copper   -   Cu Cu2+  +  2e-  →  Cu