Chapter 8

Redox reaction. What is reduction/oxidation. How do you determine if a reaction is a redox \n reaction or not?

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For a redox reaction, reduction means that electrons are \n added, whereas oxidation implies that electrons are lost. \n • Some useful mnemonics: \n • Oxidation Is Loss; Reduction Is Gain (OIL RIG) \n • Loss of Electrons Is Oxidation; Gain of Electrons Is \n Reduction \n • (LEO the lion says GER)

Determination of oxidation number.

Because compounds are electrically neutral, the Oxidation \n Numbers in any compound will sum to zero. \n For a polyatomic ion, Oxidation Numbers must sum to the \n charge on the ion. (The oxidation number of a monatomic \n ion is equal to its charge.) \n 54

Oxidation of metals in aqueous solution (Activity series)

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Metals listed at the top of the activity series are called the \n active metals. \n Metals at the bottom of the series, such as copper, silver, \n platinum, and gold, are called the noble metals because \n they have very little tendency to react. \n Reactions in which hydrogen ion is reduced to hydrogen gas \n are known as hydrogen displacement reactions. \n 62

Go over the sample problems of the lecture ppt.

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Half reaction and balancing simple oxidation/reduction reactions

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Galvanic cell and circuit

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A galvanic cell is a device that \n converts the energy released in a \n spontaneous chemical reaction into \n electrical energy. This is \n accomplished by the transfer of \n electrons from one substance to \n another. \n • The electron transfer process \n involves two changes. For instance, \n zinc is oxidized by releasing 2 \n electrons, and the copper is reduced \n by picking up those 2 electrons.

Set up of a galvanic cell

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Ohm’s law

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\n Alkaline cells each produce 1.5 V, but \n larger cells can sustain a current \n through the external circuit for a \n longer time. \n • The current (I) is the rate of electron \n flow, measured in amperes (amps, A). \n For smaller cells, milliamps, mA, is \n used. \n • Ohm’s Law relates voltage, current, \n and resistance \n • Ohm's Law

Preferred oxidation states (memorize)

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Batteries

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A battery is a system for the direct conversion \n of chemical energy to electrical energy. \n • Batteries are found everywhere in today’s \n society because they are convenient, \n transportable sources of stored energy. \n • The “batteries” shown here are more correctly \n called galvanic cells. \n • A series of galvanic cells that are wired \n together constitutes a true battery – like the \n one in your car. \n • ©McGraw-Hill Education/Eric Misko/Elite Images

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Different types of batteries and the cell reactions

Half reactions of different types of batteries

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Each process of reduction-oxidation (redox) is expressed as a half-reaction:

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Capacitors, super capacitors and batteries, advantages/disadvantages

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Hybrid vehicles, fuel cells and how fuel cell works

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Hydrogen storage

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Hydrogen production

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