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Slide 1 of 31 Chemistry 21.3. © Copyright Pearson Prentice Hall Slide 2 of 31 Electrolytic Cells DVDs have made it possible to store large amounts of.

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Presentation on theme: "Slide 1 of 31 Chemistry 21.3. © Copyright Pearson Prentice Hall Slide 2 of 31 Electrolytic Cells DVDs have made it possible to store large amounts of."— Presentation transcript:

1 Slide 1 of 31 Chemistry 21.3

2 © Copyright Pearson Prentice Hall Slide 2 of 31 Electrolytic Cells DVDs have made it possible to store large amounts of data in a very small space. A laser is used to transfer data to the master DVD. You will read about electrochemical processes that require (rather than produce) electrical energy. 21.3

3 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 3 of 31 Electrolytic vs. Voltaic Cells How do voltaic and electrolytic cells differ? 21.3

4 Slide 4 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolytic vs. Voltaic Cells An electrolytic cell is an electrochemical cell used to cause a chemical change through the application of electrical energy. The process in which electrical energy is used to bring about such a chemical change is called electrolysis. 21.3

5 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 5 of 31 Electrolytic vs. Voltaic Cells The key difference between voltaic and electrolytic cells is that in a voltaic cell, the flow of electrons is the result of a spontaneous redox reaction, whereas in an electrolytic cell, electrons are pushed by an outside power source, such as a battery. 21.3

6 Slide 6 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolytic vs. Voltaic Cells 21.3

7 Slide 7 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolytic vs. Voltaic Cells 21.3

8 Slide 8 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolytic vs. Voltaic Cells 21.3

9 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 9 of 31 Electrolysis of Water What products are formed by the electrolysis of water? 21.3

10 Slide 10 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolysis of Water The products of the electrolysis of water are hydrogen gas and oxygen gas. 21.3

11 Slide 11 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolysis of Water 21.3

12 Slide 12 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolysis of Water Balancing the Equation 21.3

13 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 13 of 31 Electrolysis of Brine What oxidation and reduction reactions occur during the electrolysis of brine? 21.3

14 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 14 of 31 Electrolysis of Brine During electrolysis of brine, chloride ions are oxidized to produce chlorine gas at the anode. Water is reduced to produce hydrogen gas at the cathode. 21.3

15 Slide 15 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolysis of Brine Balancing the Equation 21.3

16 © Copyright Pearson Prentice Hall Slide 16 of Electrolysis of Brine Electrolytic Cells > Battery

17 Slide 17 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Electrolysis of Brine To produce chlorine and sodium hydroxide in electrolytic cells, electricity is passed through brine, a sodium chloride solution. 21.3

18 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 18 of 31 Using Electrolysis in Metal Processing How are electrolytic cells used in metal processing? 21.3

19 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 19 of 31 Using Electrolysis in Metal Processing Electrolytic cells are commonly used in the plating, purifying, and refining of metals. 21.3

20 Slide 20 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells 21.3 Using Electrolysis in Metal Processing Electroplating and Electroforming Electroplating is the deposition of a thin layer of a metal on an object in an electrolytic cell. Electroforming is a process in which an object is reproduced by making a metal mold of it at the cathode of a cell.

21 Slide 21 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Using Electrolysis in Metal Processing The cathode is the object to be plated. The anode is the plating metal. 21.3

22 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 22 of 31 Using Electrolysis in Metal Processing Animation 27 Take an atomic-level look at how electricity can bring about a chemical change.

23 Slide 23 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Using Electrolysis in Metal Processing Electrowinning In electrowinning, impure metals are purified in an electrolytic cell. Aluminum is produced from alumina at the cathode of an electrowinning cell. 21.3

24 Slide 24 of 31 © Copyright Pearson Prentice Hall > Electrolytic Cells Using Electrolysis in Metal Processing Electrorefining In the process electrorefining, a piece of impure metal is made the anode of the cell. It is oxidized to the cation and then reduced to the pure metal at the cathode. 21.3

25 © Copyright Pearson Prentice Hall Slide 25 of 31 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 21.3 Section Quiz

26 © Copyright Pearson Prentice Hall Slide 26 of Section Quiz. 1. In electrolysis, an electric current is used to a.cause a chemical change. b.produce a battery. c.generate heat. d.run a motor

27 © Copyright Pearson Prentice Hall Slide 27 of Section Quiz. 2. During the electrolysis of water, the region around the anode a.changes color. b.turns basic. c.turns acidic. d.remains neutral.

28 © Copyright Pearson Prentice Hall Slide 28 of Section Quiz. 3.Choose the correct words for the spaces. In the net reaction for the electrolysis of water, __________ is/are produced at the cathode and ___________ is/are produced at the anode. a.hydrogen, oxygen b.oxygen, hydrogen c.hydrogen ions, hydroxide ions d.hydroxide ions, hydrogen ions

29 © Copyright Pearson Prentice Hall Slide 29 of Section Quiz. 4. In the process of electroplating, the metal is deposited by a.reduction at the anode. b.reduction at the cathode. c.oxidation at the anode. d.oxidation at the cathode.

30 © Copyright Pearson Prentice Hall Slide 30 of Which of the following processes does NOT use the principles behind an electrolytic cell? a.electroforming b.electrowinning c.electrorefining d.electrochemical energy production 21.3 Section Quiz.

31 © Copyright Pearson Prentice Hall Electrolytic Cells > Slide 31 of 31 Concept Map 21 Solve the Concept Map with the help of an interactive guided tutorial.

32 END OF SHOW


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