Question

In making a specific galvanic cell, explain how one decides on the electrodes and the solutions to use in the cell.

Short answer

In making a specific galvanic cell, one must first identify the intended redox reaction and the species involved in each half-cell reaction. Appropriate electrodes and electrolyte solutions are then chosen based on the redox reactions, with electrodes made of, or coated with, the conductor involved in the respective half-cell reactions and electrolyte solutions containing the ions involved in the reactions. Additionally, factors affecting electrode potentials, such as concentration of ions in the solution and temperature, should be considered while choosing the electrodes and solutions to meet any specific voltage or physical property requirements.

Step-by-step solution

Understand the basic components of a galvanic cell

A galvanic cell consists of two half-cells, each containing an electrode (a solid conductor, usually metal) and an electrolyte solution (a liquid containing ions that can conduct electricity). One half-cell functions as the anode (oxidation occurs), while the other functions as the cathode (reduction occurs). These two half-cells are connected through a salt bridge that helps to maintain electrical neutrality in both half-cells.

Identify the requiredRedox reactions

To determine which electrodes and solutions to use, it is important to know the overall redox reaction that the galvanic cell is intended to facilitate. The redox reaction consists of oxidation (loss of electrons) and reduction (gain of electrons) reactions occurring at the anode and cathode, respectively. Some examples of common redox reactions in galvanic cells include: - Zn(s) + Cu^2+(aq) → Zn^2+(aq) + Cu(s) - Ag(s) + Cl^-(aq) → AgCl(s) + e^-

Determine species involved in redox reactions

Once you have identified the overall redox reaction, you can determine the species involved in each half-cell reaction. This will help you choose the appropriate electrodes and solutions for each half-cell. For example, in the reaction: Zn(s) + Cu^2+(aq) → Zn^2+(aq) + Cu(s), zinc is involved in the oxidation reaction (Zn(s) → Zn^2+(aq) + 2e^-) and copper is involved in the reduction reaction (Cu^2+(aq) + 2e^- → Cu(s)).

Choose appropriate electrodes

The electrodes for each half-cell should be made of, or coated with, the conductor involved in the respective redox reactions. In the example above, a zinc electrode should be used for the anode (where oxidation occurs) and a copper electrode should be used for the cathode (where reduction occurs).

Choose appropriate electrolyte solutions

The electrolyte solutions in each half-cell should contain the ions involved in the redox reactions. This will facilitate the transfer of electrons between the two half-cells and support the overall redox reaction. In the example above, the anode half-cell should contain a zinc salt solution (e.g., ZnSO4) while the cathode half-cell should contain a copper salt solution (e.g., CuSO4).

Consider factors affecting electrode potentials

The choice of electrodes and solutions can also be influenced by factors such as the electrode potentials, concentration of ions in the solution, and temperature. These factors can affect the overall cell potential or voltage, which is the driving force for the redox reaction to occur. If the intended galvanic cell is required to produce a specific voltage or have specific physical properties, these factors should be considered while choosing the electrodes and solutions. To summarize, the process of making a specific galvanic cell involves understanding the basic components, identifying the redox reactions, choosing appropriate electrodes and solutions, and considering factors that affect electrode potentials.