Chemistry of solutions
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Chemistry of solutions Presentation Transcript

  • 1. D’ CHEMISTRY OF
    SOLUTIONS
  • 2. SOME DEFINITIONS
    A solution is a _______________ mixture of 2 or more substances in a single phase.
    One constituent is usually regarded as the SOLVENTand the others as SOLUTES.
  • 3. SOME DEFINITIONS
    • Solutions are homogeneous mixtures of two or more pure substances.
    • 4. In a solution, the solute is dispersed uniformly throughout the solvent.
  • PARTS OF A SOLUTION
    SOLUTE – the part of a solution that is being dissolved
    (usually the lesser amount)
    SOLVENT – the part of a solution that dissolves the solute
    (usually the greater amount)
    Solute + Solvent = Solution
    O2
    N2
    NH3
    H2O
    H2O
    Isopropyl alcohol
    H2O
    Ethyl alcohol
    Iodine
    Alcohol
    H2O
    Salt
  • 5. WHICH IS WHICH 1st ROUND
    • Identify the solute and solvent in each of the following solutions.
    • 6. 1.0 g of sugar dissolved in 100 g of water.
    • 7. 50 mL of water mixed with 20 mL isopropyl alcohol
    • 8. A tincture of Iodine is prepared with 0.10 g I2 and 10.0 mL of ethyl alcohol.
    • 9. 40 % ethanol a rubbing alcohol.
    • 10. Sugar is the smaller quantity that is dissolving. Therefore it the solute and water is the solvent.
    • 11. Since both water and isopropyl alcohol are liquids, the one smaller volume, is the solute and water is the solvent.
    • 12. Iodine is the solute and ethyl alcohol is the solvent.
    • 13. Ethanol is the solvent and water is the solute.
  • WHICH IS WHICH 2nd ROUND
    • Identify the solute and solvent in each of the following solutions.
    • 14. 10 g NaCl and 100 g of water.
    • 15. 50 mL ethanol and 10 mL H2O
    • 16. 2.0 L oxygen and 8.0 L nitrogen.
    • 17. 100 g silver and 40 g mercury.
    • 18. 100 mL H2O and 5.0 g sugar
  • TYPE OF SOLUTION
    • Gas
    • 19. Liquid
    • 20. Solid
  • SOME EXAMPLES OF SOLUTION
    Air
    Oxygen
    Nitrogen
    H2O
    CO2
    Soda water
    H2O
    Vinegar
    Acetic acid
    H2O
    Sugar
    Sugar syrup
    Ag
    Hg
    Dental
    amalgam
    Brass or
    Steel
    Carbon
    Zinc
    Iron
    Copper
  • 21. D’ UNIVERSAL SOLVENT
    WATER
    H2O
  • 22. HOW SOLUTIONS ARE
    FORMED?
  • 23. DEFINE SOLUTIONS
    • Solutions are homogeneous mixtures of two or more pure substances.
    • 24. In a solution, the solute is dispersed uniformly throughout the solvent.
  • How Does a Solution Form?
    Solvent molecules attracted to surface ions.
    Each ion is surrounded by solvent molecules.
    Enthalpy (DH) changes with each interaction
    broken or formed.
    Ionic solid dissolving in water
  • 25.
    • The ions are solvated
    (surrounded by solvent).
    • If the solvent is water, the ions are hydrated.
    • 26. The intermolecular forces.
    How Does a Solution Form?
  • 27.
    • solvation is an interaction of a solute with the solvent, which leads to stabilization of the solute in the solution.
    What is solvation?
  • 28. KINDS OF SOLUTION
    • Dilute
    small amount of solute dispersed in the solvent
    • Concentrated
    large amount of solute is dissolved in the solvent
  • 29. Types of Solutions Based on Solute Concentration…
    • Hypotonic
    (lower solute concentration) to the solution
    • Hypertonic
    (higher solute concentration) to the solution
  • 30.
    • Isotonicsolutions are equal in their solute concentrations. We say that they
    are isotonic to each other.
    Types of Solutions Based on Solute Concentration…
  • 31. QUESTIONS THAT NEEDS SOLUTIONS…
    • How does a solid dissolve into a liquid?
    • 32. What ‘drives’ the dissolution process?
    • 33. What are the energetics of dissolution?
  • WHAT IS DISSOLUTION ?
    is the process by which a solid, 
    liquid or gas 
    forms a solution 
    in a solvent.
  • 34. DISSOLUTION PROCESS IN SOLIDS…
    In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent.
  • 35. DISSOLUTION PROCESS IN LIQUIDS & GASES…
    For liquids and gases, the molecules must be compatible with those of the solvent for a solution to form.
  • 36. dry
    Dissolution vs Reaction
    NiCl2(s)
    Ni(s) + HCl (aq)
    NiCl2(aq) + H2(g)
    Dissolution is a physical change—you can get back the original solute by evaporating the solvent.
    If you can’t, the substance didn’t dissolve, it reacted.
  • 37. DEFINE
    SOLUBILITY?
  • 38. What is Solubility?
    refers to the maximum amount of solute, expressed in grams, that can be dissolved in 100 g of water at a specific temperature & pressure.
  • 39.
    • Soluble
    a substance that dissolves in a solvent
    • Insoluble
    a substance that does not dissolve in a solvent (sand is insoluble in water)
    VOCABULARY
  • 40. LABORATORY ACTIVITY 2.7SOLUBILITY IN WATER
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    SOLUBLE
    SOLUBLE
    INSOLUBLE
    S/SOLUBLE
    SOLUBLE
    SOLUBLE
    INSOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
  • 41. VOCABULARY
    • Immiscible
    Two liquids that are insoluble
    (Oil & Vinegar)
    • Miscible
    Two liquids that are soluble in each other
    (Alcohol & Water)
    IMMISCIBLE
    MISCIBLE
    MISCIBLE
    S/MISCIBLE
  • 42.
    • Saturated solution
    • 43. Solvent holds as much solute as is possible at that temperature.
    • 44. Undissolved solid remains in flask.
    • 45. Dissolved solute is in dynamic equilibrium with solid solute particles.
    Degree of Saturation
  • 46. Degree of Saturation
    • Unsaturated Solution
    • 47. Less than the maximum amount of solute for that temperature is dissolved in the solvent.
    • 48. No solid remains in flask.
  • Degree of Saturation
    • Supersaturated
    • 49. Solvent holds more solute than is normally possible at that temperature.
    • 50. These solutions are unstable; crystallization can often be stimulated by adding a “seed crystal” or scratching the side of the flask.
  • FACTORS AFFECTING
    SOLUBILITY
  • 51. Factors Affecting Solubility
    Chemists use the axiom
    “like dissolves like”
    • Polar substances tend to dissolve in polar solvents.
    • 52. Nonpolar substances tend to dissolve in nonpolar solvents.
  • LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
    IMMISCIBLE
    MISCIBLE
    MISCIBLE
    S/MISCIBLE
    SOLUBLE
    SOLUBLE
    INSOLUBLE
    INSOLUBLE
  • 53. Temperature
    Generally, the solubility of solid solutes in liquid solvents increases with increasing temperature.
  • 54. LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
  • 55. Temperature
    • The opposite is true of gases.
    Higher temperature drives gases out of solution.
    • Carbonated soft drinks are more “bubbly” if stored in the refrigerator.
    • 56. Warm lakes have less O2 dissolved in them than cool lakes.
  • Molecular Size
    • The larger the molecules of the solute are, the larger is their molecular weight and their size.
    • 57. It is more difficult it is for solvent molecules to surround bigger molecules.
    • 58. If all of the above mentioned factors all excluded, a general rule can be found that larger particles are generally less soluble. 
    • 59. If the pressure, and temperature are the same than out of two solutes of the same polarity, the one with smaller particles is usually more soluble.
  • LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
  • 60. Effect of Stirring
    • Stirring only increases the speed of the process - it increases the movement of the solvent that exposes solute , thus enabling solubility.
    • 61. As molecules in liquid substances are in constant move, the process would take place anyway, but it would take more time.
  • LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
    DISSOLVES
    FASTER
    TAKES TIME
    DISSOLVES
    DISSOLVES
    FASTER
    TAKES TIME
    DISSOLVES
  • 62. Factors Affecting Solubility
    The stronger the intermolecular attractions between solute and solvent, the more likely the solute will dissolve.
    Example: ethanol in water
    Ethanol = CH3CH2OH
    Intermolecular forces = H-bonds; dipole-dipole; dispersion
    Ions in water also have ion-dipole forces.
  • 63. Factors Affecting Solubility
    • Glucose
    (which has hydrogen bonding) is very soluble in water.
    • Cyclohexane
    (which only has dispersion forces)is not water-soluble.
  • 64. Factors Affecting Solubility
    Vitamin A is soluble in nonpolar compounds
    (like fats).
    Vitamin C is soluble in water.
  • 65. Which vitamin is water soluble and which is fat soluble?
    HEALTHAPPLICATION
  • 66. Gases in Solution
    In general, the solubility of gases in water increases with increasing mass.
    Why?
    Larger molecules have stronger dispersion forces.
  • 67. Gases in Solution
    The solubility of liquids and solids does not change appreciably with pressure.
    But, the solubility of a gas in a liquid is directly proportional to its pressure.
    Increasing pressure above solution forces more gas to dissolve.
  • 68. Henry’s Law
    States that:
  • 69. Henry’s Law
    Sg = kPg
    Where:
    Sg is the solubility of the gas;
    k is the Henry’s law constant for that gas in that solvent;
    Pgis the partial pressure of the gas above the liquid.