1 / 11

Chapter 19: Electrochemistry

Chapter 19: Electrochemistry. Lecture Topics 1. Balancing Redox /Oxidation-Reduction Reactions. 2. Voltaic Cells 3. Electrolysis 4. Corrosion. Chapter 19: Oxidation Reduction Reactions. (1) Oxidation: Loss e- Increase in Oxidation Number Zn (s) Zn 2+ + 2e -

kedma
Download Presentation

Chapter 19: Electrochemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 19: Electrochemistry • Lecture Topics • 1. Balancing Redox/Oxidation-Reduction Reactions. • 2. Voltaic Cells • 3. Electrolysis • 4. Corrosion

  2. Chapter 19: Oxidation Reduction Reactions • (1) Oxidation: Loss e- • Increase in Oxidation Number • Zn(s)Zn2+ + 2e- • (2) Reduction: Acceptance of e- • Decrease in Oxidation Number • Cl2(g) + 2e- 2Cl-

  3. Balancing Oxidation-Reduction Equations: Use Half-Reaction Method • The half-reactions for • Sn2+(aq) + 2Fe3+(aq)  Sn4+(aq) + 2Fe3+(aq) • are • Sn2+(aq)  Sn4+(aq) +2e- • 2Fe3+(aq) + 2e- 2Fe2+(aq) • Oxidation Half-Reaction: electrons are products. • Reduction Half-Reaction: electrons are reactants.

  4. Half-Reaction Method for Balancing Oxidation-Reduction Equations • 1. Separate the equation into the two half-reactions. Write down the two half reactions. • 2. Balance each half reaction: a. First balance all elements other than H and O. b. Then balance O by adding water. c. Then balance H by adding H+ if have acidic solution. d. Finish by balancing charge by adding electrons.

  5. Half-Reaction Method for Balancing Oxidation-Reduction Equations • 3. Multiply each half reaction to make the number of electrons equal. 4. Add the two half-reactions and simplify. To simplify, remove components common to both reactant and product sides. 5. Check!

  6. Example • Balance: (acidic) • MnO4- (aq) + C2O42- (aq)  Mn2+ (aq) + 2CO2 (g) • The two incomplete half reactions are • MnO4-(aq)  Mn2+(aq) • C2O42-(aq)  2CO2(g)

  7. Problem • Complete and balance the following equations, and identify the oxidizing and reducing agents • (a) Cr2O72- (aq) + I-(aq) Cr3+(aq) + IO3-(aq) • (acidic solution)

  8. Balancing Oxidation-Reduction Reactions: Basic Medium • When the reaction occurs in an alkaline solution, follow the rule listed below to balance H. • 1. Balance O with H2O. Then balance H with H+. • 2. Must neutralize H+. Use coefficient in front or H+, and add equivalent/same number of OH- to both sides of the half-reaction. • 3. For the side with both H+ and OH-, write H2O. • 4. Resume regular steps for balancing the half-reaction.

  9. Problem • Complete and balance the following half reaction(s) In each case, indicate whether oxidation or reduction occurs. • (d) OH- O2(g) • (basic solution) • (e) SO32-(aq) SO42-(aq) • (basic solution)

  10. Problem • Complete and balance the following equations, and identify the oxidizing and reducing agents. Pb(OH)42- (aq) + ClO- (aq) PbO2(s) + Cl-(aq) • (basic solution)

  11. Problem 19.2-B: Use the Half Reaction Method • (in a basic solution) Bi(OH)3 + SnO2 2- SnO32- + Bi

More Related