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CHEMISTRY 161 Chapter 4

CHEMISTRY 161 Chapter 4. CHEMICAL REACTIONS. 2 HgO (s) → 2Hg (l) + O 2(g) aq 1. properties of aqueous solutions 2. reactions in aqueous solutions a) precipitation reactions b) acid-base reactions (proton transfer) c) redox reactions (electron transfer). 1.PROPERTIES OF AQUEOUS SOLUTIONS.

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CHEMISTRY 161 Chapter 4

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  1. CHEMISTRY 161 Chapter 4

  2. CHEMICAL REACTIONS 2 HgO(s)→ 2Hg(l) + O2(g) aq 1. properties of aqueous solutions 2. reactions in aqueous solutions a) precipitation reactions b) acid-base reactions (proton transfer) c) redox reactions (electron transfer)

  3. 1.PROPERTIES OF AQUEOUS SOLUTIONS homogeneous mixture of two or more substances solute solvent substance in a small amount substance in a large amount N2 gas phase O2 (air) Ag solid phase Au (alloys) H2O liquid phase NaCl (sea water)

  4. EXP1 iodine in ethyl alcohol (C2H5OH) does not conduct electricity (molecular solid) I2 EXP2 table salt in water (H2O) does conduct electricity (ionic solid) Na+Cl-

  5. AQUEOUS SOLUTION solute water (H2O) solutes solution conducts electricity solution does not conduct electricity EXP3 electrolytes non-electrolytes

  6. electrolytes non-electrolytes solution conducts electricity solution does notconduct electricity

  7. non-electrolyte weak electrolyte strong electrolyte ionic compounds (NaCl, KF) NaOH HCl H2SO4 methanol sugar ethanol water CH3COOH HCOOH HF EXP5 dark medium bright

  8. SOLUTION concentration

  9. SOLUTION percentage concentration % = g [solute] / g solvent X 100 12 g of sodium chloride are solved in 150 g of water. Calculate the percentage concentration 8 %

  10. SOLUTION solubility of a solute number of grams of solute that can dissolve in 100 grams of solvent at a given temperature • 36.0 g NaCl can be dissolve in 100 g of water at 293 K

  11. GAS PHASE SOLUTION Saturn solvent H2/He solute CH4, PH3

  12. LIQUID SOLUTION Europa solvent H2O solute MgSO4

  13. SOLID SOLUTION Triton solvent N2 solute CH4

  14. ELECTROLYTES ionic compounds (NaCl, KF) NaOH HCl H2SO4 methanol sugar ethanol water CH3COOH HCOOH HF

  15. migrating negative and positive charges NaCl Kohlrausch

  16. DISSOCIATION ‘breaking apart’ EXP5 NaCl (s) → Na+ (aq) + Cl- (aq) NaOH (s) → Na+ (aq) + OH- (aq) HCl (g) → H+ (aq) + Cl- (aq) Ca(NO3)2 (s) → Ca2+(aq) + 2 NO3- (aq) strong electrolytes are fully dissociated polyatomic ions do NOT dissociate

  17. δ- O H H δ+ δ+

  18. SOLVATION cations anions

  19. SOLVATION non-electrolyte

  20. NaCl (s) → Na+ (aq) + Cl- (aq) strong electrolytes are fully dissociated → CH3COOH (aq) H+ (aq) + CH3COO- (aq) ← weak electrolytes are not fully dissociated reversible reaction (chemical equilibrium)

  21. CHEMICAL REACTIONS • properties of aqueous solutions • 2. reactions in aqueous solutions • a) precipitation reactions • b) acid-base reactions (proton transfer) • c) redox reactions (electron transfer)

  22. 2.1. PRECIPITATION REACTIONS solution 1 + solution 2 solution 1 solution 2

  23. 2.1. PRECIPITATION REACTIONS formation of an insoluble product (precipitate) NaCl(aq) + AgNO3(aq) AgCl(s) + NaNO3(aq) EXP 6

  24. insoluble compounds • M+ compounds (M = H, Li, Na, K, Rb, Cs, NH4) • 2. A- compounds (A = NO3, HCO3, ClO3, Cl, Br, I) • (AgX, PbX2) • 3. SO42- • (Ag, Ca, Sr, Ba, Hg, Pb) • 4. CO32-, PO43-, CrO42-, S2- • (Ag, Ca, Sr, Ba, Hg, Pb)

  25. balanced molecular equation NaCl(aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq) (table to determine which compound precipitates)

  26. balanced ionic equation 1. NaCl(s) → Na+(aq) + Cl-(aq) 2. AgNO3(s) → Ag+(aq) + NO3-(aq) 3. Na+(aq) + Cl-(aq) + Ag+(aq)+ NO3-(aq)→ AgCl(s) + Na+ (aq) + NO3-(aq) spectator ions

  27. Ba(NO3)2 (aq) + Na2SO4 (aq) Ba(NO3)2(aq) + Na3PO4(aq) Cs2CrO4(aq) + Pb(NO3)2(aq) • which compound falls out? 2. balanced molecular equation3. balanced ionic equations4. identify spectator ions

  28. CHEMICAL REACTIONS • properties of aqueous solutions • 2. reactions in aqueous solutions • a) precipitation reactions • b) acid-base reactions (proton transfer) • c) redox reactions (electron transfer)

  29. ACIDS AND BASES ACIDS HAc→ H+ (aq) + Ac- (aq) ionization HCl (g) → H+ (aq) + Cl- (aq) BASES MOH→ M+ (aq) + OH- (aq) Arrhenius (1883) NaOH (s) → Na+ (aq) + OH- (aq)

  30. IDENTIFICATION Litmus Paper acid red Säure base blue Base EXP7

  31. ACIDS AND BASES BASES ACIDS and NEUTRALIZE EACH OTHER HAc (aq) + MOH (aq) → MAc (aq) + H2O HCl (aq) + NaOH (aq) → NaCl (aq) + H2O acid + base salt + water

  32. ACIDS AND BASES Na+ ≈ 10-10 m ≈ 10-15 m H+

  33. ACIDS AND BASES HCl (g) → H+ (aq) + Cl- (aq) H+(aq) + H2O H3O+(aq) HCl (g) + H2O → H3O+ (aq) + Cl- (aq) one step hydronium ion

  34. (aq) (l) (aq) (aq) acid base hydronium ion

  35. cation hydronium ion

  36. PROPERTIES OF ACIDS • acids have a sour taste • vinegar – acetic acid • lemons – citric acid 2. acids react with some metals to form hydrogen 2 HCl(aq) + Mg(s) → MgCl2(aq) + H2(g) EXP8 3. acids react with carbonates to water and carbon dioxide 2 HCl(aq) + CaCO3(s) → CaCl2(aq) + [H2CO3] H2CO3 → H2O(l) + CO2(g) EXP9 4. some acids are hygroscopic H2SO4 (conc)

  37. BASES • bases have a bitter taste 2. bases feel slippery soap 3. aqueous bases and acids conduct electricity

  38. EXAMPLES KOH(aq) and HF(aq) Mg(OH)2(aq) and HCl(aq) Ba(OH)2(aq) and H2SO4(aq) NaOH(aq) and H3PO4(aq) (stepwise)

  39. ACIDS proton donors HAc → H+ (aq) + Ac- (aq) BASES proton acceptor B + H+ (aq) → BH+ (aq) Bronsted (1932)

  40. strong electrolyte HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq) HNO3(aq) + H2O(l) → H3O+(aq) + NO3-(aq) weak electrolyte CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) NH3(aq) + H2O(l) NH4+ + OH- donor versus acceptor

  41. CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) NH3(aq) + H2O(l) NH4+(aq)+ OH-(aq) H2O(l) + H2O(l) H3O+(aq) + OH-(aq) water can be either an acid or a base AUTO DISSOCIATION

  42. monoprotic acids HF, HCl, HBr, HNO3, CH3COOH diprotic acid H2SO4→ H+(aq) + HSO4-(aq) HSO4-(aq) H+(aq) + SO42-(aq) EXP10 triprotic acid H3PO4 H+(aq) + H2PO4-(aq) H2PO4-(aq) H+(aq) + HPO42-(aq) HPO42-(aq) H+(aq) + PO43-(aq)

  43. CHEMICAL PROPOERTIES 1. Non-metal oxides react with water to form an acid (acetic anhydrides) + H2O + H2O + H2O Cl2O7, SO2, Br2O5

  44. CHEMICAL PROPERTIES 2. Soluble metal oxides react with water to form a base (base anhydrides) + H2O + H2O MgO, Al2O3

  45. NAMING ACIDS AND BASES binary acids prefix hydro- the suffix –ic to the stem of the nonmetal name followed by the word acid

  46. NAMING ACIDS AND BASES oxo acids acids contain hydrogen, oxygen, plus another element main group 5 HNO3 nitricacid HNO2 nitrousacid H3PO4 phosphoricacid H3PO3 phosphorousacid

  47. main group 6 H2SO4 sulfuricacid H2SO3 sulfurousacid main group 7 HClO4 perchloricacid HClO3 chloricacid HClO2 chlorousacid HClO hypochlorousacid

  48. Acids in the Solar System Europa H2SO4(s) Venus H2SO4(g)

  49. Acids in the Interstellar Medium

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