Electrode reactions and the cell reaction

A cell diagram, with its designation of the left and right electrodes, allows us to write reaction equations for the cell. These equations are written according to the convention that electrons enter at the right terminal and leave at the left terminal. 

At each electrode there is an electrode reaction, or half-reaction, one for reduction at the right electrode and the other for oxidation at the left electrode. The reaction equations for the electrode reactions include electrons as either a reactant (at the right terminal) or a product (at the left terminal). The cell reaction describes the overall chemical change its reaction equation is the sum of the equations for the two electrode reactants with cancellation of the electrons. 

For instance, we can write the electrode reactions of the cell of Fig. 14.1 as follows. 

As written here, the stoichiometric numbers of the electrons have the same absolute value (2) in both reaction equations. This allows the electrons to cancel when we add the electrode 

The cell of Fig. 14.1 has a single electrolyte phase with essentially the same composition at both electrodes, and is an example of a cell without liquid junction or cell without transference. As an example of a cell with transference, consider the cell diagram 

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Write the electrode reactions and the cell reactions for the following galvanic cells, and calculate the standard emf s of the cells at 25°C. Determine the positive electrodes ... 

The characteristic of the lead-acid battery is that both electrodes are based on the chemistry of lead. The discharge-charge process is known as the double sulfate reaction, with the positive and negative electrodes being the seats of a dissolving-precipitating (and not some kind of solid-state ion transport or film formation) mechanism of the lead sulfate. The cell, the electrode reactions and the cell reaction are ... 

It is entirely arbitrary whether we show a particular electrode at the left or the right of the cell diagram, although often there is a preference to place the eleetrode attached to the positive terminal at the right. If we exchange the positions of the two electrodes in the diagram, then we must reverse the reaction equations for the electrode reactions and the cell reaction. 

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