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A reducing agent donates electrons in a redox reaction, while the oxidizing agent acquires them. Redox reactions generate electric potential, which can be harnessed to create electricity, as in the potato battery experiment. The spontaneity of redox reactions depends on the stability of their products. Scientists can predict this based on electrical potential, which is found by breaking the reaction down into half-reactions and using a standard reduction potential table. The direction of electron flow depends on the strength of the reducing agent.
A reducing agent is a term in chemistry that refers to an atom that donates electrons in a redox reaction. The atom that acquires those electrons is said to be reduced. The reduced atom is called the oxidizing agent; it takes the electrons from the oxidized atom, which is another name for the reducing agent.
If an electron leaves an atom it has to go somewhere else, so the processes of oxidation and reduction go hand in hand. Together, they form a class of reactions called redox reactions, also known as redox reactions. These reactions generate a flow of electrons, so they have electric potential.
Scientists can harness the potential of oxidation-reduction reactions to create electricity. This is the concept behind the potato battery, a common science experiment. The experimenter places a zinc lead and a copper lead in the potato. The free ions in the potato facilitate the flow of electrons between the two conductors by preventing a buildup of positive charge around the conductors which would halt the reaction. Electrons flow from lead acting as a reducing agent to lead acting as an oxidizing agent; in the process, the atoms of the reducing lead enter the potato solution, while the ions surrounding the oxidizing lead are converted to metal on the surface of the original lead.
If an atom is an oxidizing agent in a reaction, it would be a reducing agent if the reaction were reversed. Whether an atom acts as an oxidizing agent or as a reducing agent depends on the direction in which the reaction is spontaneous. Reactions occur spontaneously if their products are relatively more stable than their reactants. Scientists can predict the spontaneity of redox reactions based on their electrical potential.
To evaluate a potential redox reaction, scientists first break the reaction down into half reactions, which represent loss of electrons, or reduction. In the case of potato, zinc and copper can both form ions with positive charge 2. Therefore, the half-reactions are Zn+2 + 2e- –> Zn and Cu+2 + 2e- –> Cu.
The next step is to find the direction of electron flow. The experimenter does this using a standard reduction potential table, which provides a potential for each half-reaction. If the direction of the half-reaction is reversed, its potential has the same magnitude, but its sign changes. The half-reaction potential of zinc is -0.76 volts, while that of copper is 0.34 volts.
This means that zinc is a stronger reducing agent than copper, so in this reaction zinc acts as a reducing agent. The overall reaction in the potato battery is Zn + Cu+2 -> Zn+2 + Cu, which generates 1.10 volts of electricity in the wire connecting the leads. If the zinc lead were replaced with a silver lead, however, copper would be the reducing agent, since the silver half-reaction, Ag+ + e-, has a standard reduction potential of 0.80 volts. The battery would generate 0.46 volts.
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