3.3 Elements from the sea

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3.3 Elements of the Sea
Electrolysis as Redox Reactions
When electricity is passed through molten or aqueous compounds (only these as they contain free
electrons) the compound is broken down by electrolysis
Molten compounds
If ionic compounds are melted their charged ions become free to move and carry a
Electrons are lost or gained by ions at the electrodes (oxidation at the anode, reduction at
An ions migrate to the anode Cations migrate to the cathode
Nonmetals, apart from Hydrogen Metals
The electrolysis of solutions is much easier to carry out that
electrolysis of molten compounds.
When an ionic compound dissolves the ions become free to move and
carry the current.
The gases can also be collected for identification.
Manufacturing Chlorine
NaCl is molten so that ions can move
The positive carbon anode oxidises the
Cl ions.
The negative iron cathode reduces the
Na+ ions.

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Electrolysis of Water
Water takes part in electrolysis also so it can be hard to predict the products at the
electrodes.…read more


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