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Chapter 7 Reactions in Aqueous Solutions

Chemistry B2A. Chapter 7 Reactions in Aqueous Solutions. Reactions in Aqueous Solutions. Ionic compounds. Aqueous solution : solvent is water. Reactions in Aqueous Solutions. Chemical reactions that occur in water. In our body reactions occur in the aqueous solution. Water in our body.

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Chapter 7 Reactions in Aqueous Solutions

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  1. Chemistry B2A Chapter 7 Reactions in Aqueous Solutions

  2. Reactions in Aqueous Solutions Ionic compounds Aqueous solution: solvent is water

  3. Reactions in Aqueous Solutions Chemical reactions that occur in water. In our body reactions occur in the aqueous solution.

  4. Water in our body • About 60% of our body. • Most of the reactions occur in aqueous solution. • Participates in many biochemical reactions. • Transports reactants and products from one place in our • body to another. • 5. Eliminates the waste materials from cells and our body (urine).

  5. Why does a chemical reaction occur? Several driving forces: • Formation of a solid • Formation of water • Transfer of electrons • Formation of a gas

  6. Why does a chemical reaction occur? Several driving forces: • Formation of a solid • Formation of water • Transfer of electrons • Formation of a gas

  7. Formation of a solid Precipitation reactions Precipitate KI + Pb(NO3)2  ?

  8. Ions Hydrated by H2O Hydration Ionic Compounds When an ionic compound dissolves in water, ions are produced.

  9. Ionic Compounds • Soluble solid:it completely dissolves in water (ions are formed). • Slightly soluble solid: it partially dissolves in water. • Insoluble solid: it does not dissociate in water (almost). Ionic compounds = Salts

  10. Ionic Compounds All nitrates (NO3-) and acetate (CH3COO-) are soluble in water. Most salts of Na+, K+, and NH4+ are soluble in water. Most chlorides (Cl-) and sulfates (SO42-) are soluble in water. (except AgCl, PbCl2, BaSO4, CaSO4, PbSO4) Most carbonates (CO32-), phosphates (PO43-), Sulfide (S2-), and hydroxides (OH-) are insoluble in water. (except NaOH, KOH, Ba(OH)2, Ca(OH)2, and NH4OH)

  11. electrolyte + - Electrolytes bulb Electrolyte:conducts an electric current. Na+ Cl- Ionization (Dissociation) NaCl → Na+ + Cl- strong electrolytes:molecules dissociate completely into ions (NaCl). weak electrolytes:molecules dissociate partially into ions (CH3COOH). nonelectrolytes:molecules do not dissociate into ions (DI water).

  12. Formation of a solid Precipitation reactions Precipitate KI + Pb(NO3)2  ?

  13. Aqueous Solution(ionic compounds) aqueous solution: solvent is water H2O Dissociation (Ionization) KI(s) K+(aq) + I-(aq) KI K+ I- Pb(NO3)2 H2O Pb(NO3)2(s) Pb2+(aq) + 2NO3-(aq) NO3- Pb2+ NO3-

  14. Aqueous Solution(ionic compounds) KI Pb(NO3)2 K+ I- Pb2+ NO3- 2KI(aq) + Pb(NO3)2(aq)  PbI2(s) + 2KNO3(aq)

  15. total charge on left side = total charge on right side balanced equation 2As3+(aq) + 3s2-(aq)  As2S3(s) 2KI(aq) + Pb(NO3)2(aq)  PbI2(s) + 2KNO3(aq) Molecular equation: Complete Ionic equation: 2K+(aq) + Pb2+(aq) + 2I-(aq) + 2NO3-(aq)  PbI2(s) + 2K+(aq) + 2NO3-(aq) 2K+(aq) + Pb2+(aq) + 2I-(aq) + 2NO3-(aq)  PbI2(s) + 2K+(aq) + 2NO3-(aq) Spectator ions Net ionic equation: Pb2+(aq) + 2I-(aq)  PbI2(s)

  16. Why does a chemical reaction occur? Several driving forces: • Formation of a solid • Formation of water • Transfer of electrons • Formation of a gas

  17. Acids and Bases Acids: sour Bases: bitter or salty

  18. Acids and Bases Arrhenius definition: Acid: produces H3O+ (H+) in water. CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) H3O+ (Hydronium ion): H+(aq) + H2O(l) H3O+(aq) Base: produces OH- in water. H2O NaOH(s) Na+(aq) + OH-(aq) NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

  19. Acids and Bases Weak acid and base:it is partially ionized in aqueous solution. produces less H+ and OH- CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) NH3(aq) + H2O(l) NH4+(aq) + OH-(aq) Strong acid and base:it is completely ionized in aqueous solution. produces more H+ and OH- HCl(aq) + H2O(l) Cl-(aq) + H3O+(aq) NaOH(aq) + H2O(l) Na+(aq) + OH-(aq)

  20. Acid-Base Reactions Neutralization A strong acid and a strong base react together toproduce a salt and water. NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) +  Na+(aq) + Cl-(aq) + H2O(l) H+(aq) + OH-(aq) H2O(l) The only chemical change is the formation of water.

  21. Why does a chemical reaction occur? Several driving forces: • Formation of a solid • Formation of water • Transfer of electrons • Formation of a gas

  22. Oxidation and Reduction reactions (redox) e- 2Na(s) + Cl2(g) 2NaCl(s) Na → Na+ + e- Cl + e-→ Cl- Metal + Nonmetal : Transfer of electrons Oxidation and Reduction reactions (redox)

  23. Oxidation and Reduction reactions (redox) oxidation:it is the loss of electrons. reduction:it is the gain of electrons. Zn(s) + Cu2+(aq)  Zn2+(aq) + Cu(s) redox reaction Zn(s)  Zn2+(aq) + 2e- Zn is oxidized (reducing agent) Cu2+(aq) + 2e-  Cu(s) Cu2+ is reduced (oxidizing agent)

  24. C gains O and loses H is oxidized (reducing agent) O gains H Is reduced (oxidizing agent) Oxidation and Reduction reactions (redox) oxidation:is the gain of oxygen / loss of hydrogen. reduction:is the loss of oxygen / gain of hydrogen. CH4(s) + 2O2(g)  CO2(g) + 2H2O(g) redox reaction single replacement reaction and combustion reactions redox reactions double replacement reactions  non redox

  25. Classification of chemical reactions Chemical reactions Precipitation Reactions Oxidation-Reduction Reactions Acid-Base Reactions Synthesis (combination) Reactions (Reactants are elements.) Decomposition (Analysis) Reactions (Products are elements.) Combustions Reactions

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