Question

Tarnish on copper is the compound CuO. A tarnished copper plate is placed in an aluminum pan of boiling water. When enough salt is added so that the solution conducts electricity, the tarnish disappears. Imagine that the two halves of this redox reaction were separated and connected with a wire and a salt bridge. Part A Calculate the standard cell potential given the following standard reduction potentials: Al3++3e−→Al;E∘=−1.66 V Cu2++2e−→Cu;E∘=0.340 V Express your answer to two decimal places and include the appropriate units.

Answer 1

Answer:

The standard cell potential is 2.00 V

Explanation:

Step 1: Data given

Cu is cathode because of higher EP

Al3++3e−→Al       E∘=−1.66 V     anode

Cu2++2e−→Cu    E∘=0.340 V    cathode

Step 2: Balance both equations

2*(Al → Al3+-3e−)       E∘=1.66 V    

3*(Cu2++2e−→Cu)    E∘=0.340 V

Step 3: The netto equation

2 Al + 3Cu2+ +6e- → 2Al3+ + 3Cu -6e-

2 Al + 3Cu2+  → 2Al3+ + 3Cu

Step 4: Calculate the standard cell potential

E∘cell = E∘cathode - E∘anode

E∘cell = E∘ Cu2+/Cu - E∘ Al3+/Al

E∘cell =0.340 V - (-1.66) = 2.00 V

The standard cell potential is 2.00 V