Chemistry
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- Category: Science
- Date Submitted: 05/27/2012 03:56 AM
- Pages: 12
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4. Oxidation-Reduction reactions are increasingly important as a source of energy.
1: Explain the displacement of metals from solution in terms of transfer of electrons.
- When an active metal is placed in a solution containing ions of a less active metal, the active metal displaces the less active metal from solution.
- This occurs because a more active metal atom loses one or more electrons and becomes a positive ion.
- The electrons lost are transferred to the ions of the less active metal, resulting in them becoming metal atoms.
- Oxidation is loss of electrons (or gain in oxidation number)
- Reduction is gain of electrons (or loss in oxidation number)
- Oxidation-reduction reactions are also called redox or electron transfer reactions.
If an Iron nail is placed in a solution of blue copper (II) salt, some of the iron nail dissolves
[pic]
At the same time, the blue colour of Cu2+ ions disappears and a dark copper coating appears on the nail surface
[pic]
The overall reaction is:
[pic]
The electrons lost by iron atoms undergoing oxidation are used to reduce copper (II) ions to copper atoms.
PRAC 1 : Perform a first-hand investigation to identify the conditions under which a galvanic cell is produced.
Galvanic cells require:
- The transfer of electrons between two dissimilar electrodes.
- An electrolyte (a salt solution)
- Salt bridge to allow transfer of ions between half-cells.
- Conductive wire between two electrodes.
- Each electrode must be in a 1M salt solution containing its own ion.
2: Identify the relationship between displacement of metal ions in solution by other metals to the relative activity of metals.
In reacting the more active metal atom (M) changes to a metal ion (M+) by losing one or more electrons to form a cation.
The ability of metal to lose electrons is measured on the electrochemical series (see Standard Reduction Potentials table.) The elements are arranged in order of their...
1: Explain the displacement of metals from solution in terms of transfer of electrons.
- When an active metal is placed in a solution containing ions of a less active metal, the active metal displaces the less active metal from solution.
- This occurs because a more active metal atom loses one or more electrons and becomes a positive ion.
- The electrons lost are transferred to the ions of the less active metal, resulting in them becoming metal atoms.
- Oxidation is loss of electrons (or gain in oxidation number)
- Reduction is gain of electrons (or loss in oxidation number)
- Oxidation-reduction reactions are also called redox or electron transfer reactions.
If an Iron nail is placed in a solution of blue copper (II) salt, some of the iron nail dissolves
[pic]
At the same time, the blue colour of Cu2+ ions disappears and a dark copper coating appears on the nail surface
[pic]
The overall reaction is:
[pic]
The electrons lost by iron atoms undergoing oxidation are used to reduce copper (II) ions to copper atoms.
PRAC 1 : Perform a first-hand investigation to identify the conditions under which a galvanic cell is produced.
Galvanic cells require:
- The transfer of electrons between two dissimilar electrodes.
- An electrolyte (a salt solution)
- Salt bridge to allow transfer of ions between half-cells.
- Conductive wire between two electrodes.
- Each electrode must be in a 1M salt solution containing its own ion.
2: Identify the relationship between displacement of metal ions in solution by other metals to the relative activity of metals.
In reacting the more active metal atom (M) changes to a metal ion (M+) by losing one or more electrons to form a cation.
The ability of metal to lose electrons is measured on the electrochemical series (see Standard Reduction Potentials table.) The elements are arranged in order of their...