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Acids and Bases

Explore the world of acids, bases, and gas-forming reactions. Learn about oxidation-reduction reactions, oxidation numbers, recognizing redox reactions, and metal displacement. Unravel the mysteries of chemical interactions.

francescarter
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Acids and Bases

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  1. Acids and Bases continued

  2. 130 10 0 0 Which of the following is a strong acid? • Hydrofluoric acid • Chloric acid • Sulfurous acid • Hydrobromic acid • Acetic acid

  3. Gas-Forming Exchange Reaction

  4. Reaction of Metal Carbonates with Acids CaCO3(s) + 2CH3COOH(aq) Ca(CH3COO)2(aq) + H2CO3(aq) H2CO3(aq) H2O(l) +CO2(g) Carbonic acid is unstable and releases carbon dioxide gas Total Ionic Equation: CaCO3(s) + 2CH3COOH  Ca2+ + 2CH3COO- + H2O + CO2(g) Net Ionic Equation is the same

  5. Reaction of Metal Sulfites and Sulfides with Acids CaSO3(s) + 2HCl(aq) CaCl2(aq) + H2SO3(aq) H2SO3(aq) H2O +SO2(g) Net Ionic Equation: CaSO3(s) + 2H+(aq) Ca2+(aq) + H2O(l) + SO2(g) Na2S(aq) + 2HCl(aq) 2NaCl(aq) + H2S(g) Net Ionic Equation: S2-(aq) + 2H+(aq) H2S(g)

  6. 130 10 0 0 Which of the following is a gas forming reaction? • Na2CO3+Ba(OH)2 • AgNO3+Na2S  • ZnCO3+HNO3  • HCl+CuSO4 

  7. Oxidation-Reduction Reactions

  8. Oxidation-Reduction Reactions Oxidation –loss of electrons Reduction – gain of electrons Oxidation and Reduction always occur together oxidizing agent – substance that causes oxidation reducing agent – substance that cause reduction

  9. OxidationIsLoss ReductionIsGain 4 e- Mn4+(O2-)2 Mn (s) + O2 (g)  MnO2 (s) Manganese is oxidized

  10. Common Oxidizing and Reducing Agents

  11. Copper and Nitric Acid

  12. Nitric acid is a powerful oxidizing agent • The nitrogen in the nitric acid is reduced to NO2 (or sometimes NO) • 4HNO3(aq)+Cu(s) Cu(NO3)2(aq)+2NO2(g)+2H2O(l) -2 e- +2 e-

  13. 130 10 0 0 Which species is the reducing agent in the Cu + HNO3 reaction? • Cu • NO2 • Cu(NO3)2 • HNO3 • H2O

  14. Copper Oxide and Hydrogen Gas 2Cu+O2 2CuO 2CuO+2H2 2Cu+2H2O

  15. Oxidation Numbers • To keep track of the movement of electrons in reactions we assign oxidation numbers to each element. Treat all interactions as ionic and assign electrons to the most electronegative element to give it its usual charge. • Sometimes real but usually not.

  16. Oxidation Number Rules • All pure elements have Ox# = 0 • Monatomic ions have Ox# = charge • Hydrogen is +1 unless with a metal then -1 • Fluorine is -1 in all compounds • Oxygen is -2 unless attached to fluorine or itself H-O-O-H both O’s are -1 • Other halogens are -1 unless attached to F or O

  17. Binary compounds • CuCl2 Cu is +2, Cl is -1, the actual charges • SCl2 Cl is assigned -1 • Neutral compound so sum of ox# = 0 • S + 2 × (-1) = 0, S is +2, assigned charge

  18. Finding Oxidation Numbers What is the oxidation number of S in H2SO4? • H  +1 • O  -2 • neutral compound, thus sum equals zero • 4O  4  -2 = -8 • 2H  2  +1 = +2 • 0 = +2 + S + (-8) S = +6

  19. 130 10 0 0 What is the oxidation number of N in HNO3? • +7 • +6 • +5 • +4 • +3

  20. Oxidation State What is the oxidation state of Cr in Cr2O72-? • O  -2 • ion, thus sum equals charge = -2 • 7O  7  -2 = -14 • -2 = 2 × Cr + (-14) • 2 × Cr = +12 • Cr = +6

  21. 130 10 0 0 What is the oxidation number of Br in BrF4+? • +7 • +6 • +5 • +4 • +3

  22. Recognizing Redox Reactions

  23. 130 10 0 0 Which of the following is a redox reaction? • CaCO3CaO+CO2(g) • HNO3+KOHKNO3+H2O • BaCl2+H2SO4BaSO4(s)+2HCl • Ca+2H2OCa(OH)2+H2(g) • Na2S+2HCl2NaCl+H2S(g)

  24. Metal + Acid Displacement

  25. Activity Series of Metals

  26. Activity Series of Metals • metals higher in series react with compounds of those below • metals become less reactive to water top to bottom • metals become less able to displace H2 from acids top to bottom

  27. Potassium + Water

  28. Activity Series of Metals Zn(s) + CuSO4(aq) ZnSO4(aq) + Cu(s) Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s) Fe(s) + 2HCl(aq) FeCl2(aq) + H2(g) Zn(s) + 2HBr(aq) ZnBr2(aq) + H2(g)

  29. Metal + Metal Salt Displacement

  30. 130 10 0 0 Which of the following reactions does NOT happen? • Cu(s)+H2SO4(aq)CuSO4(aq)+H2(g) • 2HNO3(aq)+2K(s)2KNO3(aq)+H2(g) • FeCl2(aq)+Zn(s)ZnCl2(s)+Fe(s) • Ca(s)+2H2O(l)Ca(OH)2(aq)+H2(g) • Cu(s)+2AgNO3(aq)2Ag(s)+Cu(NO3)2(aq)

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