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ZingPath: Types of Reactions

Batteries, Chemicals, and Potential Difference

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Types of Reactions

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Batteries, Chemicals, and Potential Difference

Chemistry

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You will investigate the change in cell potential when the concentration of electrolytes in a galvanic cell are increased and decreased.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Describe the components of a galvanic cell as consisting of two electrodes immersed in two electrolyte solutions connected by a salt bridge and external circuit.
  • Explain how changing the concentration of the electrolyte solution in the anode compartment of a galvanic cell affects the cell’s potential.
  • Explain how changing the concentration of the electrolyte solution in the cathode compartment of a galvanic cell affects the cell’s potential.
  • Describe the flow of electrons from anode to cathode in a galvanic cell in terms of oxidation and reduction.
  • Identify and label the parts of an electrolytic cell and the direction of electron flow.

Everything You'll Have Covered

Through the processes of oxidation and reduction, the electrons involved in reactions are either gained or lost. This transfer of electrons can be measured in a galvanic cell, which uses chemical reactions to produce a flow of electrons. The cell is split into two electrodes, in which oxidation and reduction reactions take place. Oxidation reactions take place on the anode of the cell and represent the loss of electrons, while reduction reactions take place on the cathode of the cell and represent the gain of electrons.

As electrons are gained and lost, they create electricity that is transferred throughout the galvanic cell. This galvanic cell then is able to produce a particular value of energy due to the transfer of electrons during oxidation and reduction. The cell's potential energy is called its reduction potential.

When using electrolyte solutions, it is important to use a standard condition by which all other cell potential reductions can be measured as the concentration of the solution changes. The standard reduction potential is considered a measurement taken under the "standard conditions" of 1 mole of a solution or 1 atmosphere of a gas.

The reduction potential that is present on each electrode depends on the solution's concentration. As the solution's concentration changes, the reaction activity changes, thereby affecting oxidation and reduction. A change in the oxidation or reduction of the reaction represents an increase or decrease in the transfer of electrons. Therefore, a solution with a change in concentration will have a change in reduction potential. The Nernst equation, named after Walther Nernst, the German physical chemist who first formulated it, is used to calculate cell potential when conditions are not 1 mole for solutions or 1 atmosphere for gases. The Nernst equation measures this potential by calculating the voltage of the reduction and the oxidation reactions present in the cell. The sum of these two voltage amounts is the cell's total potential.

Tutorial Details

Approximate Time 20 Minutes
Pre-requisite Concepts Students should have knowledge of how electrons flow from a negative source to a positive destination. They should also know how electrochemical cells are formed from a redox reaction’s ability to release electrons.
Course Chemistry
Type of Tutorial Experiment
Key Vocabulary anode, battery, cathode