Electrochemistry 1

Electrochemistry 1

• 1.
  1 Oxidation–Reduction Reactions Electrochemistry-1 By: Dr.Munawar Hussain Chemistry at Work
• 2.
  Everyday Oxidation-Reduction Reactions An oxidation–reductionreaction  provides us with energy from food  provides electrical energy in batteries  occurs when iron rusts 4Fe(s) + 3O2(g) 2Fe2O3(s) 2
• 3.
  Transfer of Electrons Anoxidation–reduction reaction  transfers electrons from one reactant to another Oxidation Is a Loss of electrons (OIL) Zn(s) Zn2+(aq) + 2e Reduction Is a Gain of electrons (RIG) Cu2+(aq) + 2e Cu(s) 3
• 4.
  Oxidation and Reduction 4
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  Oxidized or Reduced? 5
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  Zn and Cu2+ 6 oxidation Zn(s)Zn2+(aq) + 2e- Silvery metal reduction Cu2+(aq) + 2e- Cu(s)
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  ElectronTransfer from Znto Cu2+ Oxidation: electron loss Reduction: electron gain 7
• 8.
  Learning Check Identify eachof the following as: 1) oxidation or 2) reduction A. Sn(s) Sn4+(aq) + 4e− B. Fe3+(aq) + 1e− Fe2+(aq) C. Cl2(g) + 2e− 2Cl−(aq) 8
• 9.
  Solution Identify each ofthe following as: 1) oxidation or 2) reduction 1 A. Sn(s) Sn4+(aq) + 4e− 2 B. Fe3+(aq) + 1e− Fe2+(aq) 2 C. Cl2(g) + 2e− 2Cl−(aq) 9
• 10.
  Writing Oxidation and ReductionReactions Write the separate oxidation and reduction reactions for the following equation. 2Cs(s) + F2(g) 2CsF(s) Each cesium atom loses an electron to form a cesium ion. 2Cs(s) 2Cs+(s) + 2e− oxidation Each fluorine atom gains an electron to form a fluoride ion. F2(s) + 2e– 2F−(s) reduction 10
• 11.
  Learning Check In light-sensitivesunglasses, UV light initiates an oxidation–reduction reaction. uv light Ag+ + Cl− Ag + Cl A. Which reactant is oxidized? B. Which reactant is reduced? 11
• 12.
  Solution In light-sensitive sunglasses,UV light initiates an oxidation-reduction reaction. uv light Ag+ + Cl− Ag + Cl A. Which reactant is oxidized? Cl − Cl− Cl + 1e− B. Which reactant is reduced? Ag+ Ag+ + 1e− Ag 12
• 13.
  Learning Check Identify thesubstances that are oxidized and reduced in each of the following reactions: A. Mg(s) + 2H+(aq) Mg2+(aq) + H2(g) B. 2Al(s) + 3Br2(g) 2AlBr3(s) 13
• 14.
  Solution Identify the substancesthat are oxidized and reduced in each of the following reactions: A. Mg is oxidized Mg(s) Mg2+(aq) + 2e− H+ is reduced 2H+ + 2e− H2 B.Al is oxidized 2Al 2Al3+ + 6e− Br is reduced 2Br + 2e− 2Br− 14
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  Oxidation–Reduction in Biological Systems Inbiological systems, oxidation may involve  the loss of H  the gain of O In biological systems, reduction may involve  the gain of H  the loss of O 15
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  Oxidation–Reduction in BiologicalSystems (continued) 16
• 17.
  Summary of Oxidationand Reduction 17