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ions - particles with an excess (neg. ions) or
deficiency (pos. ions) of electrons |
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electrolyte
- a substance which will
conduct electricity when melted or dissolved in water.
eg.
HCl, H2SO4, NaCl, NaOH |
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electrodes
- electrical contacts which will attract or repel the ions
anode
- positive
cathode - negative |
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electrolysis
- a process which causes chemical changes by passing electric
current through the liquid |
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oxidation - particles lose electron |
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reduction - particles gain electrons |
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Ampere-hour rating - the product of current provided and the length of time it
may run |
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Electrochemical cells -Two dissimilar metals
placed in an electrolytic solution can cause a chemical reaction capable of
producing an electric current. |
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voltaic cell - a type of primary cell using zinc
an copper electrodes and aqueous sulfuric acid as the electrolyte. |
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Primary cell - a cell for which the chemical
reactants will need to be replaced. It is not rechargeable. eg. Dry cell
(flashlight batteries) |
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Storage cell - a cell which is rechargeable by
reversing the current through the cell to restore the chemical energy. eg.
lead- acid cells (car batteries) |
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the zinc cathode breaks down to zinc ions and 2
e . |
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the sulfuric acid forms hydronium and sulfate
ions . |
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the hydronium ions are repelled to the copper
electrode where they collect electrons leaving the electrode positively
charged (anode). This reaction produces water and hydrogen gas molecules. |
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Electrons can thus flow through a conductor from
the cathode (zinc) to the anode (copper) |
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Attaching a base material to the cathode , a
plating material (gold, silver, nickel etc) to the anode and using a salt
of the plating material as the the electrolyte, the plating material can be
deposited on the base. |
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Faraday's laws |
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The mass of material deposited on the electrode
depends
1. Directly on the quantity of charge passed through the liquid
2. Directly on the atomic mass of the plating material
3. Inversely on the valence of the plating material |
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thermocouple
- a circuit for which the conductor is a combination of two
dissimilar metals. If two junctions are held at different temperatures an
electric current will be induced. |
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Seebeck effect - the conversion of heat energy
to electrical energy by means of a thermocouple |
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Peltier effect - converting electrical energy
into heat energy beyond the normal heat loss due to resistance |
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Notes