Chemical Concept Demonstrated: Electrochemical work with voltaic or galvanic cells
|The beaker contains a solution of H2SO4.
A copper wire electrode along with a magnesium electrode are inserted into the solution.
The wires are connected to a flashbulb.
Alternately, a normal light bulb may be used.
The flashbulb is set off.
Explanation (including important chemical equations):
The standard-state reduction potentials are:
|Mg 2+ (aq) + 2 e- ---> Mg (s)||Eo = -2.37 V|
|Cu 2+ (aq) + 2 e- ---> Cu (s)||Eo = 0.34 V|
The reaction that has an overall positive cell potential is therefore
|Mg (s) ---> Mg 2+ (aq) + 2 e-||Eo = 2.37 V|
|2 H + (aq) + 2 e - ---> H2 (g)||Eo = 0.00 V|
|Mg (s) + 2 H + (aq) ---> Mg 2+ (aq) + H2 (g)||Eo cell = 2.37 V|
Electrons flow from the magnesium electrode to the copper electrode through the external circuit, setting off the flashbulb.