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Reduction/Oxidation

Reduction/Oxidation. REDOX. Reduction. Gain of electrons by element Element gaining electrons-- charge goes down , becoming more negative One method of purifying metal. Oxidation. Loss of electrons by element Element losing electrons-- charge goes up , becoming more positive

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Reduction/Oxidation

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  1. Reduction/Oxidation REDOX

  2. Reduction • Gain of electrons by element • Element gaining electrons--charge goes down, becoming more negative • One method of purifying metal

  3. Oxidation • Loss of electrons by element • Element losing electrons--charge goes up, becoming more positive • (Rusting iron) • Reduction and oxidation ALWAYS go together. • One element gives electrons to the other.

  4. LEO the lion goes “GER!”

  5. Remember electron dot structures? • Symbol of element with dots around it representing valence electrons • Can be used to show REDOX processes .Mg.

  6. Mg atom: 12 (+) protons 12 (-) electrons 0 charge Mg0 Mg ion: 12 (+) protons 10 (-) electrons + 2 charge Mg+2 Remember Ions v. Atoms?

  7. Show Mg forming ion with dot structures: • Mg  Mg2+ + 2e- ( ) • (Atom) (ion) (electrons lost) (No charge) • Is Magnesium reduced or oxidized? • Where did the 2 electrons go?

  8. Mg + 2Ag+ Mg2+ + Ag + Ag • What is oxidized? Reduced?

  9. Mg + 2Ag+ Mg2+ + Ag + Agoxidizedreduced • What caused the magnesium to be oxidized? • Silver. • This is called the Oxidizing agent • What caused the silver to be reduced? • Magnesium • This is called the Reducing agent See Modeling Matter p.124-125 for more!

  10. REDOX WORKSHEET • Label charges: Elements all alone have no charge (0) • Polyatomic ions can be found on chart • Metals and nonmetals are on periodic table • LEO--Charge goes up • GER--Charge goes down • Reduction also method of purifying metal

  11. 1. Cu (s) + AgNO3 (aq)  Ag (s) + Cu(NO3)2 0 +1 -1 0 +2 -1 Cu + 2AgNO3 2Ag + Cu(NO3)2 Oxidized: Cu Reduced: Ag

  12. 2. Mg (s) + Cu(NO3)2 (aq)  Cu (s) + Mg(NO3)2 0 +2 -1 0 +2 -1 Mg + Cu(NO3)2 Cu + Mg(NO3)2 • Oxidized: Mg • Reduced: Cu

  13. 3. 2Al2O3 (aq)  4Al (s) + 3O2 (g) +3 -2 0 0 Al2O3 (aq)  Al (s) + O2 (g) • Oxidized: O • Reduced: Al

  14. 4. 4Fe (s) + 3O2 (g)  2Fe2O3 (s) 0 0 +3 -2 • Fe (s) + O2 (g)  Fe2O3 (s) • Oxidized: Fe • Reduced: O

  15. 5. Cu (s)+ Cl2 (l)  CuCl2 (aq) 0 0 +2 -1 • Cu (s) + Cl2 (l)  CuCl2 (aq) • Oxidized: Cu • Reduced: Cl

  16. 6. Pt plating of junked cars in the coastal waters of Hawaii Fe(s) + Pt(NO3)3(aq) Pt(s)+Fe(NO3)3(aq) 0 +3 -1 0 +3 -1 Fe + Pt(NO3)3 Pt + Fe(NO3)3 • Oxidized: Fe • Reduced: Pt

  17. 7. Old defunct pencil sharpeners Al (s) + Fe(NO3)3 (aq)  Al(NO3)3 (aq) + Fe (s) 0 +3 -1 +3 -1 0 Al + Fe(NO3)3 Al(NO3)3 + Fe • Oxidized: Al • Reduced: Fe

  18. 8. Tin cans rusting 4Fe (s) + 3SnCl4 (aq)  4FeCl3 (aq) + 3Sn 0 +4 -1 +3-1 0 Fe + SnCl4 FeCl3 + Sn • Oxidized: Fe • Reduced: Sn

  19. 9. Galvanized pipes Zn (s) + CuCl2 (aq)  ZnCl2 (aq) + Cu (s) 0 +2 -1 +2-1 0 Zn + CuCl2 ZnCl2 + Cu • Oxidized: Zn • Reduced: Cu

  20. 10. Crisis at 3-Mile Island due to Zirconium losing its protective coating. Zr (s) + 2H2O (l)  ZrO2 (aq) + 2H2 0 +1 -2 +4 -2 0 Zr (s) + H2O (l)  ZrO2 (aq) + H2 • Oxidized: Zr • Reduced: H

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