MSJ2e_Ch19_ISM1_June26_p816 - Chapter 19 Electrochemistry...

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Unformatted text preview: Chapter 19: Electrochemistry and Its Applications Chapter 19: Electrochemistry and Its Applications Teaching for Conceptual Understanding Students who had difficulty with oxidation-reduction chemistry in Chapter 4 will probably have trouble understanding electrochemistry. A review (in or out of class) of the principles of oxidation is essential. Continue to reinforce an understanding of chemistry on the three levels (macroscopic, symbolic, and particulate) by showing actual electrochemical cells and electrolysis reactions, writing balanced chemical equations for the processes, and drawing particulate diagrams to illustrate the charges on a molecular level. Students often think of the salt bridge as a conduit for the solutions in the half-cells. Explain on a particulate level the migration of the salt ions into each half-cell as the reaction progresses. Be prepared to answer the question: “Why doesn’t the solution fall out of the salt bridge when you turn it over?” Because we also refer to electrochemical cells as galvanic cells, voltaic cells, and batteries, students sometimes get confused and think there are four different cells to learn. Choose one of these names and use it consistently. Distinguish between electrolytic and galvanic cells when describing electrolysis. Understanding how to use the information in Table 19.1, Standard Reduction Potentials in Aqueous Solution, is key to predicting electrochemical processes. Take the time to explain this table thoroughly. Suggestions for Effective Learning Students often confuse the type of reaction occurring at an electrode. A good mnemonic is both anode and oxidation begin with a vowel and both cathode and reduction begin with a consonant. Electrochemical cells are easily assembled as shown in Figure 19.3. In lieu of a U-tube salt bridge, you can use a piece of filter paper moistened with a K 2 SO 4 solution. In addition to using a voltmeter to show the electrical energy produced, connect a simple propeller to the electrodes. An electrochemical cell made for 1 M ZnSO 4 and 1 M CuSO 4 has a cell potential of 1.10 V. Ask students if the cell potential will increase, decrease, or remain the same if the electrochemical cell were made from 0.01 M ZnSO 4 and 1.0 M CuSO 4 . As a hint, tell them to consider the problem in terms of Le Chatelier’s principle. The voltage will increase. Cooperative Learning Activities Questions, problems, and topics that can be used for Cooperative Learning Exercises and other group work are: • Questions for Review and Thought from the end of this chapter: 5, 8, 9, 81, 82, and 97 • Conceptual Challenge Problems: CP19.A, CP19.B, and CP19.C • Concept map terms: anode, battery, cathode, cell voltage, coulomb, electrochemical cell, electrode, electrolysis, electromotive force, Faraday constant, fuel cell, half-cell, half-reaction, oxidizing agent, reducing agent, salt bridge, standard hydrogen electrode, standard reduction potential, standard voltage, volt, voltaic cell....
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This note was uploaded on 09/10/2008 for the course CHE 131 taught by Professor Kerber during the Spring '08 term at SUNY Stony Brook.

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MSJ2e_Ch19_ISM1_June26_p816 - Chapter 19 Electrochemistry...

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