Suppose a galvanic cell contains one nickel electrode and one copper electrode. At 25°C, nickel has a negative reduction potential and copper has a positive reduction potential. At which electrode will reduction occur?
- I believe copper will be oxidised and nickel reduced, correct?
Can someone also explain what happens in the galvanic cell.
Thank you
Cu^2+ + 2e ==> Cu Eo = +0.34
Ni^2+ + 2e ==> Ni Eo = -0.25
To make a spontaneous cell we must have a positive cell potential; therefore,
Ni ==> Ni^2+ + 2e E = +0.25
Cu^2+ + 2e ==> Cu E = +0.34
--------------------
Ni + Cu^2+ ==> Ni^2+ + Cu Ecell = +0.59
Oxidation is the loss of electrons; which loses electrons.
Yes, you are correct. In a galvanic cell, reduction will occur at the electrode with the higher reduction potential, which is the copper electrode in this case.
To understand what happens in a galvanic cell, let's break it down into its key components and processes:
1. Electrodes: The two electrodes in the cell are made of different materials. In this case, one electrode is made of nickel, and the other electrode is made of copper.
2. Half-Reactions: Each electrode participates in a half-reaction, which involves either oxidation or reduction. The half-reaction at the nickel electrode involves the reduction of nickel ions (Ni2+) to nickel metal (Ni): Ni2+ + 2e- -> Ni (reduction). Since nickel has a negative reduction potential, it tends to gain electrons (undergo reduction) at the electrode.
Meanwhile, the half-reaction at the copper electrode involves the oxidation of copper metal (Cu) to copper ions (Cu2+): Cu -> Cu2+ + 2e- (oxidation). Since copper has a positive reduction potential, it tends to lose electrons (undergo oxidation) at the electrode.
3. Salt Bridge: A salt bridge is a path that connects the two half-cells of the galvanic cell. It consists of an electrolyte solution that allows ions to flow and maintain electrical neutrality in each half-cell. The salt bridge in this case will contain an electrolyte solution, such as potassium nitrate (KNO3).
4. Flow of Electrons and Ions: Once the circuit is completed by connecting the two electrodes with a wire, electrons flow from the nickel electrode (where oxidation occurs) to the copper electrode (where reduction occurs) through the wire. This flow of electrons generates an electric current.
Simultaneously, to maintain electrical neutrality, the salt bridge allows the flow of ions between the two half-cells. In this example, negatively charged nitrate ions (NO3-) will move from the salt bridge into the nickel half-cell to balance the positive charge of the nickel ions (Ni2+) being reduced, while positively charged K+ ions will move into the copper half-cell to balance the negative charge of the copper ions (Cu2+) being formed.
Overall, in a galvanic cell, oxidation occurs at one electrode, generating electrons, while reduction occurs at the other electrode, consuming electrons. The flow of electrons through the wire and the flow of ions through the salt bridge help complete the circuit and allow the cell to produce an electric current.