Heart pacemakers are often powered by lithium–silver chromate 'button' batteries. The overall cell reaction is 2 Li(s) + Ag₂CrO₄(s) → Li₂CrO₄(s) + 2 Ag(s) (b) Choose the two half-reactions from Appendix E that most closely approximate the reactions that occur in the battery. What standard emf would be generated by a voltaic cell based on these half-reactions?

Verified step by step guidance

Step 1: Identify the oxidation and reduction half-reactions.

Step 2: Look up the standard reduction potentials for each half-reaction from Appendix E.

Step 3: Write the oxidation half-reaction and its corresponding standard potential.

Step 4: Write the reduction half-reaction and its corresponding standard potential.

Step 5: Calculate the standard emf (E°cell) by subtracting the standard potential of the oxidation half-reaction from the standard potential of the reduction half-reaction.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Half-Reactions

Half-reactions represent the individual oxidation and reduction processes occurring in an electrochemical cell. In a voltaic cell, one half-reaction involves the loss of electrons (oxidation), while the other involves the gain of electrons (reduction). Understanding these half-reactions is crucial for determining the overall cell reaction and calculating the standard electromotive force (emf).

Standard Electrode Potential

The standard electrode potential (E°) is a measure of the tendency of a chemical species to be reduced, measured under standard conditions. Each half-reaction has a specific E° value, which can be found in electrochemical series tables. The standard emf of a voltaic cell can be calculated by subtracting the E° of the oxidation half-reaction from that of the reduction half-reaction.

Voltaic Cell

A voltaic cell, also known as a galvanic cell, converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two electrodes (anode and cathode) immersed in electrolyte solutions. The flow of electrons from the anode to the cathode generates an electric current, and the cell's emf indicates its voltage output, which is essential for applications like powering pacemakers.

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