A galvanic (voltaic) cell consists of an electrode composed of aluminum in a 1.0 M aluminum ion solution and another electrode composed of fold in a 1.0 M gold (III) ion solution connected by a salt bridge. Calculate the standard potential for this cell at 25 degrees celcius.
To calculate the standard potential (E°) for a galvanic (voltaic) cell, we can use the formula:
E°cell = E°cathode - E°anode
First, let's determine the reduction half-reaction at the cathode and anode.
At the cathode (reduction half-reaction):
Al^3+ + 3e^- -> Al (s)
At the anode (oxidation half-reaction):
Au^3+ -> Au^3+ + 3e^-
Now, we can look up the standard reduction potentials for these reactions from a table of standard electrode potentials.
The standard reduction potential for the cathode (Al^3+ + 3e^- -> Al) is -1.66 V.
The standard reduction potential for the anode (Au^3+ -> Au^3+ + 3e^-) is +1.498 V.
Substituting these values into the formula:
E°cell = E°cathode - E°anode
E°cell = -1.66 V - (+1.498 V)
E°cell = -3.158 V
Therefore, the standard potential for this cell at 25 degrees Celsius is -3.158 V.
To calculate the standard potential for the galvanic cell, we need to use the standard reduction potential values for the half-reactions involved.
The half-reaction for the reduction of aluminum ion (Al³⁺) to aluminum metal (Al) is:
Al³⁺ + 3e⁻ → Al *(s)* (reduction)
The standard reduction potential for this half-reaction is -1.66 V.
The half-reaction for the reduction of gold (III) ion (Au³⁺) to gold metal (Au) is:
Au³⁺ + 3e⁻ → Au *(s)* (reduction)
The standard reduction potential for this half-reaction is +1.50 V.
Since the standard potential of a galvanic cell is the difference between the standard reduction potentials of the reduction half-reactions, we can calculate it by subtracting the standard potential of the aluminum half-reaction from the standard potential of the gold half-reaction:
Standard Potential = Standard Reduction Potential (Au³⁺/Au) - Standard Reduction Potential (Al³⁺/Al)
Standard Potential = +1.50 V - (-1.66 V)
Standard Potential = +1.50 V + 1.66 V
Standard Potential = +3.16 V
Therefore, the standard potential for this galvanic cell at 25 degrees Celsius is +3.16 V.
Note the correct spelling of celsius.
Al(s) + Au^3+ ==> Al^3+ + Au(s)
Look up reduction potential for Al and reverse the sign. Add to the reduction potential of Au to AuIII.
Total is Eo standard cell.