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Chemistry 20.1

Chemistry 20.1. 20.1. The Meaning of Oxidation and Reduction.

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Chemistry 20.1

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  1. Chemistry 20.1

  2. 20.1 The Meaning of Oxidation and Reduction • Salt on icy roads can make driving safer, but the salt that clings to the metallic parts of cars can cause them to corrode or rust relatively quickly. This corrosion is one example of a chemical reaction called oxidation-reduction. You will learn about oxidation-reduction reactions.

  3. 20.1 What Are Oxidation and Reduction? • What Are Oxidation and Reduction? • How is the gain or loss of oxygen in a chemical reaction linked to oxidation and reduction?

  4. 20.1 What Are Oxidation and Reduction? • The substance gaining oxygen is oxidized, while the substance losing oxygen is reduced. • These reactions are called oxidation-reduction reactions and are also known as redoxreactions.

  5. 20.1 What Are Oxidation and Reduction? • Oxygen and Redox • A Bunsen burner oxidizes the methane in natural gas to carbon dioxide and water.

  6. 20.1 What Are Oxidation and Reduction? • Carbon is oxidized when charcoal burns.

  7. 20.1 What Are Oxidation and Reduction? • Iron is oxidized when it rusts.

  8. 20.1 What Are Oxidation and Reduction? • Electron Shift in Redox Reactions • How is the gain or loss of electrons linked to oxidation and reduction?

  9. 20.1 What Are Oxidation and Reduction? • Losing electrons is oxidation. Gaining electrons is reduction. • Oxidation is now defined to mean complete or partial loss of electrons or gain of oxygen. • Reduction is now defined to mean complete or partial gain of electrons or loss of oxygen.

  10. 20.1 What Are Oxidation and Reduction? • Redox Reactions That Form Ions

  11. 20.1 What Are Oxidation and Reduction?

  12. 20.1 What Are Oxidation and Reduction? • The substance that loses electrons is called the reducing agent. The substance that accepts electrons is called the oxidizing agent.

  13. for Conceptual Problem 20.1 Problem Solving 20.1 Solve Problem 1 with the help of an interactive guided tutorial.

  14. 20.1 What Are Oxidation and Reduction? • Redox With Covalent Compounds

  15. 20.1 What Are Oxidation and Reduction?

  16. 20.1 Corrosion • Corrosion • What happens to iron when it corrodes?

  17. 20.1 Corrosion • Iron, a common construction metal often used in the form of the alloy steel, corrodes by being oxidized to ions of iron by oxygen.

  18. 20.1 Corrosion • Resistance to Corrosion • Aluminum resists corrosion because it forms a protective coating of aluminum oxide.

  19. 20.1 Corrosion • Controlling Corrosion • Painting a surface protects it from corrosion. Chromium metal also serves as a protective coating.

  20. 20.1 Corrosion • Zinc blocks attached to the steel hull of this ship oxidize instead of the iron, preventing corrosion.

  21. 20.1 Section Quiz. • 20.1.

  22. 20.1 Section Quiz. • 1. Choose the correct words for the spaces. During oxidation, an element _______ electrons. During reduction, an element ________ electrons. • gains, loses • loses, gains • gains, donates • gains, accepts

  23. 20.1 Section Quiz. • 2. Choose the correct words for the spaces. During reduction, a substance may _______ oxygen or ________ hydrogen. • gain, lose • lose, gain • gain, gain • lose, lose

  24. 20.1 Section Quiz.. • 3. The element that donates electrons in a redox reaction is called the reducing agent. This means the reducing agent is always • the more active element. • the less active element. • oxidized. • reduced.

  25. 20.1 Section Quiz. • 4. Which substance is the reducing agent in the following chemical reaction? • Fe2O3 + 3CO  2Fe + 3CO2 • Fe2O3 • CO • Fe • CO2

  26. 20.1 Section Quiz. • 5. The following equations describe the corrosion of iron to iron hydroxides in moist conditions. • 2Fe(s) + O2(g) + 2H2O(l)  2Fe(OH)2(s) • 4Fe(OH)2(s) + O2(g) + 2H2O(l) 4Fe(OH)3(s) • What substances in the equations are being oxidized? • Fe(s) and Fe(OH)2(s) • the O2(g) in both reactions • the O2(g) and H2O(l) in both reactions • Fe(OH)2(s) and Fe(OH)3(s)

  27. END OF SHOW

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