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SOLUTION CHEMISTRY

SOLUTION CHEMISTRY. I. Mixtures:. mixture = a blend of two or more kinds of matter, each of which retains its own identity and properties can be physically separated (filtration, evaporation, decanting, magnetism, etc). I. MIXTURES:.

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SOLUTION CHEMISTRY

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  1. SOLUTION CHEMISTRY

  2. I. Mixtures: • mixture = a blend of two or more kinds of matter, each of which retains its own identity and properties • can be physically separated (filtration, evaporation, decanting, magnetism, etc)

  3. I. MIXTURES: • a.) homogeneous mixture = a mixture that is uniform in composition throughout • Ex: Food coloring and water • b.) heterogeneous mixture = a mixture that is NOT uniform in composition throughout • Ex:Oil and water

  4. A. Types of Mixtures: 1) solution = a homogeneous mixture

  5. A. Types of Mixtures: 2) suspension = a mixture in which the particles are so large that they settle out unless the mixture is constantly stirred or agitated • Heterogeneous mixture • Ex: Sand and water

  6. A. Types of Mixtures: 3) colloid = a mixture consisting of particles that are intermediate in size between those in solutions and those in suspensions • Heterogeneous Mixture • Ex: Milk, mayonnaise, smog, butter, whipped cream

  7. 3) Colloids • What property of a colloid helps to prevent colloid particles from settling out of a mixture? • Brownian motion = the random continuous motions of colloidal particles

  8. 3) Colloids b) Tyndall effect = visible pattern caused by the reflection of light from suspended particles in a colloid (or from suspended particles in a suspension if the particles have not settled out) • Ex: visibility of a headlight beam on a foggy night

  9. B. Comparison of solution, colloids, and suspensions

  10. B. Properties of solution, colloids, and suspensions

  11. C. Determining if a mixture is a true solution, a colloid, or a suspension: 1.) If particles settle or can be filtered out = suspension 2.) If particles do not settle or filter out shine a beam of light (Tyndall effect) through the mixture • If the Tyndall effect is observed =colloid • If the Tyndall effect is not observed = solution

  12. II. Nature of Solutions

  13. II. THE NATURE OF SOLUTIONS: 1) Solvent = the substance that does the dissolving in a solution • Typically present in the greatest amount • Typically a liquid • Water is the most common or “universal” solvent

  14. B/c water molecules are polar • The hydrogen side of each water (H2O) molecule carries a slight positive electric charge, while the oxygen side carries a slight negative electric charge. • water can dissociate ionic compounds into their positive and negative ions. • The positive part of an ionic compound is attracted to the oxygen side of water while the negative portion of the compound is attracted to the hydrogen side of water.

  15. Water won't dissolve or won't dissolve well. If the attraction is high between the opposite-charged ions in a compound, then the solubility will be low. • Ex: hydroxides exhibit low solubility in water. • Ex: nonpolar molecules don't dissolve very well in water (fats and waxes)

  16. II. THE NATURE OF SOLUTIONS: 2) Solute = substance being dissolved in a solution • Typically present in the least amount • Typically a solid

  17. A. 9 Possible Solutions Combinations: • NOT all solutions are liquids/solids! • Solutions are formed in ALL 3 states!

  18. B. Solvation • 1.) Solvation=the process of dissolving a.) First- solute particles are surrounded by solvent particles b.) Then- solute particles are separated and pulled into solution C. Johannesson

  19. B. Solvation • 2.) Dissociation = separation of an ionic solid into aqueous ions • Ex: NaCl + H2O – the Na ion and Cl ion become hydrated and gradually move away from the crystal into solution. • Each ion in the solution acts as though it were present alone: So there is only a solution containing Na+ and Cl- ions uniformly mixed with H2O particles • NaCl(s)  Na+(aq) + Cl–(aq)

  20. Animation of Salt Dissolving: http://www.northland.cc.mn.us/biology/Biology1111/animations/dissolve.html

  21. B. Solvation • 3.) Ionization = breaking apart of some polar molecules into aqueous ions • Ex: HNO3(aq) + H2O(l)  H3O+(aq) + NO3–(aq)

  22. B. Solvation • 4.) Molecular Solvation=molecules stay intact • Ex: C6H12O6(s)  C6H12O6(aq)

  23. C. Factors Affecting the Rate of Dissolving (Increases Solution Rate): • Grinding: increases surface area exposed to solvent • Stirring: allows solvent continual contact with solute • Heating: increases kinetic energy; increases mixing

  24. C. Factors Affecting the Rate of Dissolving (Increase Solution Rate):

  25. III. Electrolytes & Nonelectrolytes

  26. Many people know me as containing “electrolytes”… that just means I contain dissolved, dissociated ions!

  27. A. Electrolytes and Nonelectrolytes 1) electrolyte = a substance that dissolves in water to give a solution that conducts electric current 2) nonelectrolyte = a substance that dissolves in water to give a solution that does NOT conduct an electric current

  28. A. Electrolytes and Nonelectrolytes 3) Solutions of electrolytes can conduct electric current: a) The positive ions and the negative ions disassociate (separate) in solution. The mobile ions can move a charge from one point in the solution to another point

  29. A. Electrolytes and Nonelectrolytes 4) Solutions of nonelectrolytescannot conduct electric current: • When a nonelectrolyte dissolves in water there are NO charged particles in solution. • Ex: Solute exists as molecules

  30. A. Electrolytes and Nonelectrolytes 5) Weak Electrolytes a) Only a portion of dissolved molecules ionize

  31. A. Electrolytes and Nonelectrolytes 6) Solidionic compounds cannot conduct electric current: a) Ions are present but they are NOT mobile.

  32. - + - - + + acetic acid salt sugar A. Electrolytes and Nonelectrolytes Non- Electrolyte Weak Electrolyte Strong Electrolyte solute exists as ions and molecules solute exists as ions only solute exists as molecules only

  33. IV. Solubility

  34. A. SOLUBILITY: 1) Solubility = quantity of solute that will dissolve in specific amount of solvent at a certain temperature. (pressure must also be specified for gases). •  Ex: 204 g of sugar will dissolve in 100 g of water at 20C • soluble and insoluble are relative terms •  solubility should NOT be confused with the rate at which a substance dissolves

  35. A. SOLUBILITY: 2) saturated solution = a stable solution in which the maximum amount of solute has been dissolved. • Visual evidence: a quantity of undissolved solute remains in contact with the solution

  36. A. SOLUBILITY: 3) solubility equilibrium = state where the solute is dissolving at the same rate that the solute is coming out of solution (crystallizing). • Opposing processes of the dissolving and crystallizing of a solute occur at equal rates. • solute + solvent solution

  37. A. SOLUBILITY: 4) unsaturated solution = a solution that contains less solute than a saturated solution under existing conditions

  38. A. SOLUBILITY: 5) supersaturated solution = a solution that temporarily contains more than the saturation amount of solute than the solvent can hold • Unstable – if disturbed, the excess solute will crystallize out of solution

  39. UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form A. Solubility concentration

  40. B. 3 FACTORS EFFECTING SOLUBILITY: 1) Nature of solute and solvent a) “Like dissolves like” = rule of thumb for predicting whether or not one substance dissolves in another“Alikeness” depends on: • Intermolecular forces • Type of bonding • Polarity or nonpolarity of molecules: • ionic solutes tend to dissolve in polar solvents but not in nonpolar solvents

  41. “Like Dissolves Like” B. 3 FACTORS EFFECTING SOLUBILITY: • b.) Solvent-Solute Combinations: YES NO NO YES

  42. B. 3 FACTORS EFFECTING SOLUBILITY: 2) Pressure: • Pressure has little effect on the solubility of liquids or solids in liquid solvents. •  The solubility of a gas in a liquid solventincreases when pressure increases. It is a direct relationship.

  43. B. 3 FACTORS EFFECTING SOLUBILITY: 3) Temperature: • The solubility of a gas in a liquid solvent decreases with an increase in temperature. •  The solubility of a solid in a liquid solvent MOST OFTEN increases with an increase in temperature. However, solubility changes vary widely with temperature changes sometimes decreasing with temperature increases.

  44. V. Solubility Graph

  45. A. SOLUBILITY CURVE: • Saturated = any point on the line or ABOVE the line 2) Unsaturated = any point BELOW the line

  46. 1. What is the solubility of the following solutes in water? a) NaCl at 60ºC= b) KCl at 40ºC= c) KNO3 at 20ºC= 38g 39g 31g

  47. 2. Are the following solutions saturated or unsaturated? Each solution contains 100 g of H20. a) 31.2 g of KCl at 30ºC = b) 106g KNO3 at 60ºC= Unsaturated Saturated (on the line)

  48. 2. Are the following solutions saturated or unsaturated? Each solution contains 100 g of H20. c)40 g NaCl at 10ºC= d)150g KNO3 at 90ºC = Saturated Unsaturated

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