19 solutions and solubility

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  • What is a solution? What is a solute? What is a solvent? Example of solute and solvent (food colouring and water)
  • 19 solutions and solubility

    1. 1. SOLUTE SolutionsSOLVEN & Solubility T Solutions & Solubility
    2. 2. Solutions & Solubility SOLVENT SOLUTION SOLUTE In a solution, the A homogenous Other substances solvent is present in mixture present in a solution the largest amount (looks uniform other than the by volume, mass, or throughout) solvent. number of moles
    3. 3. Solutions & Solubility ACTIVITY 1: Examples of SolutionsObserve the samples of solutions and classify each solution under one category: Original state of solute Solvent Example Gas Gas Oxygen in air Gas Liquid CO2 in pop Hydrogen in palladium Gas Solid Liquid Gas Water droplets in air Liquid Liquid Alcohol in water Amalgams Liquid Solid (i.e. mercury in silver) Solid Gas Dust in the air Solid Liquid Sugar in water Solid Solid Copper in bronze 3
    4. 4. Solutions & Solubility ACTIVITY 1: Examples of SolutionsHydrogen in palladium: A method for storing hydrogen gasas fuel
    5. 5. Solutions & Solubility ACTIVITY 1: Examples of SolutionsAmalgam: A metal and mercury solutionBy mass: 43% to 54% mercury,~20-35% silver, ~10% copper,~2% zinc, and some tinRemains soft for ashort time and thenforms a hard anddurable compound
    6. 6. Solutions & SolubilityIdentify the components of these solutions:
    7. 7. Solutions & SolubilityCommon Types of Solutions: Alloys: Solid solutions of metalStainless steel: Iron, chromium, nickel, manganese, vanadium
    8. 8. Solutions & SolubilityCommon Types of Solutions: Alloys: Solid solutions of metal Brass: Copper and zinc
    9. 9. Solutions & SolubilityCommon Types of Solutions: Liquid solution: A solution with two or more miscible liquids Miscible = Can dissolve in Immiscible = Cannot dissolve one-another in one-another Rubbing alcohol Oil and water
    10. 10. Solutions & SolubilityCommon Types of Solutions: Gas solution: A solution of two or more gasesAir: 78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide
    11. 11. Solutions & SolubilityCommon Types of Solutions: Aqueous solution: A solution where water is the solvent Tap water
    12. 12. Solutions & SolubilityAQUEOUS SOLUTIONS: SOLUBLE VS. INSOLUBLE Not all substances dissolve equally in water. Recall the solubility table (dissolving solids in water): Although substances are classified as either soluble or insoluble in this table, substances are almost never completely insoluble or completely soluble in water. The solubility of a solute is the amount of solute that dissolves in a given quantity of solvent, at a certain temperature. For example, the solubility of sodium chloride in water at 20ºC is 36g per 100mL of water.
    13. 13. Solutions & SolubilityAQUEOUS SOLUTIONS: SOLUBLE VS. INSOLUBLE Soluble Partly or Insoluble slightly soluble More than 1g in Between 1g Less than 0.1g 100mL and 0.1g in in 100mL OR 100mL OR greater than OR Less than 0.1mol/L Between 0.01mol/L 0.1mol/L and 0.01mol/L
    14. 14. Solutions & SolubilityAQUEOUS SOLUTIONS: SATURATED VS. UNSATURATED One cannot endlessly dissolve salt in water
    15. 15. Solutions & SolubilityAQUEOUS SOLUTIONS: SATURATED VS. UNSATURATED Saturated solution: Formed when no more solute will dissolve in a solution, with excess solute present. Unsaturated solution: A solution that is not yet saturated Supersaturated solution: Formed when a solution dissolves more solute than allowed at a specific temperature. No excess solute is present.
    16. 16. Solutions & SolubilityAQUEOUS SOLUTIONS: SATURATED VS. UNSATURATED In a saturated solution with excess solute present, the rate of dissolution and precipitation are the samePbSO4(s) Pb2+(aq) + SO42-(aq)precipitate dissolved ions
    17. 17. Solutions & Solubility FACTORS THAT AFFECT THE RATE OF DISSOLVING AND SOLUBILITYACTIVITY 2: Who Can Dissolve the Most Salt?
    18. 18. Solutions & Solubility FACTORS THAT AFFECT THE RATE OF DISSOLVING AND SOLUBILITYACTIVITY 2: Who Can Dissolve the Most Salt? (10 min)1) Work in groups of 3-42) Each group will be given a graduated cylinder of salt and 250mLof water3) Try to dissolve as much salt as you can4) Try to alter the physical properties of your solvent and solute toincrease the amount of salt that you can dissolve5) You cannot add water6) You must not have precipitate in your solution, and yoursolution cannot be boiling.
    19. 19. Solutions & Solubility FACTORS THAT AFFECT THE RATE OF DISSOLVING AND SOLUBILITYACTIVITY 2: Who Can Dissolve the Most Salt? Factor Affect on rate of dissolving/solubility Temperature Higher temperatures allow more molecules to dissolve Agitation Stirring/agitation allows more molecules to dissolve Surface area Increasing the surface area allows more molecules to dissolve
    20. 20. Solutions & Solubility Temperature WARMER COOLER At higher temperatures, solvent molecules move faster, and collide with undissolved solid molecules more frequently
    21. 21. Solutions & Solubility Agitation MORE MOLECULES IN FEWER MOLECULES IN CONTACT CONTACT Agitation brings fresh solvent into contact with undissolved solid
    22. 22. Solutions & Solubility Surface Area Molecules on the inside are exposed, enabling them to collide with solvent molecules LOWER SURFACE AREA HIGHER SURFACE AREA The greater the surface area of the reactant, the greater the molecules are in contact with the solvent
    23. 23. Solutions & Solubility Factors that affect solubility
    24. 24. Solutions & Solubility Factors that affect solubility1) Molecule polarity- Compounds dissolve due to the intermolecular forces between solvent and solute molecules Sugar: Forms H-bonds with water H O H H O H H O H O H H H H H H O O O H
    25. 25. Solutions & Solubility Factors that affect solubility1) Molecule polarity- Compounds dissolve due to the intermolecular forces between solvent and solute molecules Ethanol: Forms H-bonds with water H O H O H H H O H
    26. 26. Solutions & Solubility Factors that affect solubility1) Molecule polarity- Compounds dissolve due to the intermolecular forces between solvent and solute molecules Methanol: Forms H-bonds with water
    27. 27. Solutions & Solubility Factors that affect solubility1) Molecule polarity- Compounds dissolve due to the intermolecular forces between solvent and solute molecules Octane: Cannot form H-bonds with water H H O
    28. 28. Solutions & Solubility Factors that affect solubility1) Molecule polarity Which has greater solubility in water? CH3OH vs. CH3CH2CH2CH2CH2CH3OH Which has greater solubility in oil? CH3OH vs. CH3CH2CH2CH2CH2CH3OH The more attractive intermolecular forces exist between solvent and solute molecules, the greater the solubility
    29. 29. Solutions & Solubility Factors that affect solubility1) Molecule polarityThe addition ofsolute raisesthe boiling pointof a solvent
    30. 30. Solutions & Solubility Factors that affect solubility2) Temperature- Greater temperatures result in greater solubility of most solids Which has greater solubility in water? Instant coffee powder + water at 20°C vs. Instant coffee powder + water at 70°C
    31. 31. Solutions & Solubility Factors that affect solubility2) Temperature- The greater the temperature, the lower the solubility of gases As temperature increases, gas molecules gain kinetic energy and are able to leave a solution. Gases become LESS soluble with increasing temperature.
    32. 32. Solutions & Solubility Factors that affect solubility3) Molecule charge- Molecules that are charged can form dipole-ion attractions or Van der Waals forces between solute and solvent molecules H H O O H H H H H H Na+ Cl- O O O O H H H H H H O O H H Salt: Ions exert dipole-ion attractive forces with water
    33. 33. Solutions & Solubility Factors that affect ion solubility
    34. 34. Solutions & Solubility Factors that affect ion solubility1) Ion charge- Ions with small charges tend to be soluble- Increasing the charge increases the force that holds the ions together- (i.e. phosphates, PO43+, tend to be insoluble) 1+ 1- 3+ 3-
    35. 35. Solutions & Solubility Factors that affect ion solubility2) Ion size- Small ions tend to be less soluble than large ions- Small ions bond more closely together than large ions- Thus the bond between small ions is stronger than the bond between large ions with the same charge 2+ 2- 2+ 2-
    36. 36. Solutions & Solubility Net Ionic Equations Use the solubility Chemical equation: table K2CO3(aq) + CuSO4(aq)  ?K2SO4(aq) + CuCO3(s) Ionic equation:  Anything that is aqueous must be separated into its component ions 2K+(aq) + CO32-(aq) + Cu2+(aq) + SO42-(aq)  2K+(aq) + SO42-(aq) + CuCO3(s) Net Ionic equation:  Spectator ions* are eliminated Cu2+(aq) + CO32-(aq)  CuCO3(s)*Spectator ions are ions that do not participate in the actual reaction
    37. 37. Solutions & Solubility Solubility curves A graph that displays the maximum solute that can dissolve in 100g of water at various temperatures. Why does the solubility curve of NH3 have a negative slope? NH3 is a gas. Gases become LESS soluble with increasing temperature.
    38. 38. Solutions & Solubility Solubility curves1) Is 50g of NH4Cl in 100g ofwater at 40ºC saturated,unsaturated, or supersaturated? Supersaturated2) How many grams of KNO3 candissolve in 50g of water at 70ºC? 65g3) How much water is required todissolve 60g of NaNO3 at 50ºC? 115g NaNO3 = 60g NaNO3 100g water x x = 52g water

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