Chapter Eight Solutions

Chapter 8 | Slide 2 of 55 Steve Allen/Peter Arnold, Inc. Solutions Ocean water is one of many examples of a solution in which many different substances are dissolved.

Chapter 8 | Slide 3 of 55 Solutions An example not often considered: Jewelry often involves solid solutions in which one metal has been dissolved in another metal. © Coco McCoy/Rainbow

Chapter 8 | Slide 4 of 55 Fig. 8.1 The making of a solution. The colored crystals are the solute, and the clear liquid is the solvent. Stirring produces the solution. Solutions cont’d

Chapter 8 | Slide 5 of 55 Solutions: Some Basic Terms Solution: –A _______geneous mixture composed of a _________ and a ___________ Solvent: –The component of a mixture that is present in the _____________ amount Solute: –The component of a mixture that is present in the _____________ amount –Remain ____________ distributed and do not _________ out –Can be _______________ from solvent by _________ means such as _________________

Chapter 8 | Slide 6 of 55 Solubility The ______________ amount of solute that will dissolve in a ___________ amount of solvent under a particular set of conditions

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Chapter 8 | Slide 8 of 55 Factors Affecting Solubility, I Pressure: –The solubility of gases in liquids ______________ with pressure –Carbonated beverages are bottled with a partial pressure of CO 2 > 1 atm. –As the bottle is opened, the partial pressure of CO 2 decreases and the solubility of CO 2 decreases. –Therefore, bubbles of CO 2 escape from solution.

Chapter 8 | Slide 9 of 55 Solutions Carbon dioxide escaping from an opened bottle of a carbonated beverage.

Chapter 8 | Slide 10 of 55 Factors Affecting Solubility, II Pressure has ____________ effect on the solubility of solids or liquids Temperature –The solubility of gases in liquids ________________ with increased temperature –In general, the solubility of solids in liquids increases with increased temperature

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Chapter 8 | Slide 12 of 55 Amounts of Solute in Solution Saturated Solution –A solution that contains the ________________ amount of solute that can be dissolved under the conditions at which the solution exists –Dissolved solute is in ______________ with undissolved solute Supersaturated solution –An ____________ solution that temporarily contains _________ dissolved solute than that present in a saturated solution Unsaturated Solution –A solution which contains ______ than the maximum amount of solute that can be dissolved under the conditions at which the solution exists.

Chapter 8 | Slide 13 of 55 Amounts of Solute in Solution Saturated Solution –A solution that contains the maximum amount of solute that can be dissolved under the conditions at which the solution exists –Dissolved solute is in equilibrium with undissolved solute Supersaturated solution –An unstable solution that temporarily contains more dissolved solute than that present in a saturated solution saturated-solution Unsaturated Solution –A solution which contains less than the maximum amount of solute that can be dissolved under the conditions at which the solution exists.

Chapter 8 | Slide 14 of 55 Solutions ←Fig. 8.3 In a saturated solution, the dissolved solute is in dynamic equilibrium with the undissolved solute.

Chapter 8 | Slide 15 of 55 Solutions Both solutions contain the _________ amount of solute. A Concentrated solution (left) contains a relatively large amount that could dissolve in solvent. A Dilute solution contains a relatively small amount of solute compared with the amount that could dissolve in solvent. Not Strong or Weak

Chapter 8 | Slide 16 of 55 Types of Solutions Aqueous Solutions –___________ is the solvent Nonaqueous Solutions –The solvent is something other than __________

Chapter 8 | Slide 17 of 55 Solution Formation To form a solution, solute- solute interactions and solvent-solvent interactions must be broken to form new solute-solvent interactions. Ionic solutes: Form hydrated ions Covalent solutes: Molecules are hydrated

Chapter 8 | Slide 18 of 55 Rates of Solution Formation Solute particles will be more rapidly distributed throughout a solvent when –The solute is __________ (has more ___________ ______) –The mixture is ___________ –The _______________ of the solution is ____________

Chapter 8 | Slide 19 of 55 Solubility Rules “Like Dissolves Like” –Nonpolar solutes dissolve in nonpolar solvents –Polar solutes dissolve in polar solvents Rule is not sufficient in the case of ionic solutes dissolved in water –Some ionic compounds dissolve in water, but some do not –We follow a set of experimentally-derived rules to determine which ionic compounds dissolve in water

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Chapter 8 | Slide 21 of 55 Concentration Terms Concentration –Designates the amount of __________ dissolved in a given ___________ of _____________ There are many ways of designating concentration. –Percent concentration Percent by mass (m/m) Percent by volume (v/v) Mass-volume percent (m/v) –Molarity Moles / Liter

Chapter 8 | Slide 22 of 55 Percent by Mass The mass of solute in a solution divided by the mass of the solution, multiplied by 100 Solution = solute + solvent

Chapter 8 | Slide 23 of 55 Percent by Volume Used when solute and solvent are liquids or gases The volume of solute in a solution divided by the volume of the solution, multiplied by 100 Solution = solute + solvent Note: With liquids, volumes of solute and solvent are not always additive

Chapter 8 | Slide 24 of 55 Practice: Percentage Concentrations Calculate the mass percent of 2.31 g of LiBr dissolved in 35.0 g of water Normal saline solution that is used to dissolve drugs for intravenous use is 0.92% (m/v) NaCl in water. How many grams of NaCl are required to prepare 35.0 mL of normal saline solution?

Chapter 8 | Slide 25 of 55 Solutions Identical volumetric flasks are filled to the 50.0-mL mark with ethanol and with water. When the two liquids are poured into a 100mL volumetric flask, the volume is seen to be less.

Chapter 8 | Slide 26 of 55 Solutions Fig. 8.7 When volumes of two different liquids are combined, the volumes are not additive.

Chapter 8 | Slide 27 of 55 Molarity –A Conversion Factor between the mass of solute and the volume of solution!!!

Chapter 8 | Slide 28 of 55 Molarity Problems Determine the molarity of 3 moles of CuSO 4 in enough water to make a 6L solution. How many mL of M NaCl solution must be used to obtain mol of NaCl?

Chapter 8 | Slide 29 of 55 Molarity Problems Determine the molarity of 214 g of MgCl 2 (molar mass = 95.2 g/mole) in enough water to make an 750. mL solution.

Chapter 8 | Slide 30 of 55 Molarity Problems You are asked to prepare 250. mL of a 3.00 M NaOH by starting with solid NaOH. How many grams of NaOH would you use? What steps would you follow in making the solution? (molar mass NaOH = 40.0 g/mole)

Chapter 8 | Slide 31 of 55 Making a Solution Steps for making a solution: 1.Weigh out the solute, put it in a volumetric flask. 2.Add some water, mix the solute and the solvent. 3.Add water to the line on the volumetric flask.

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Chapter 8 | Slide 33 of 55 Dilution Problems Dilution: –Adding solvent to an existing solution to decrease the solution’s concentration. Assume that these beakers contain the same solute. What is different between the two? What is the same? BEFORE DILUTION: AFTER DILUTION:

Chapter 8 | Slide 34 of 55 The Big Idea When Doing Dilution Problems THE NUMBER OF MOLES OF SOLUTE STAYS THE SAME!!!! Start with 250 mL of a 3.0 M solution of NaOH. Add enough water to have a final solution volume of 1.0 liter. What is the new concentration of NaOH?

Chapter 8 | Slide 35 of 55 Dilution Problems Describe how you would prepare 1.0 L of a 0.10 M solution of sulfuric acid from a 3.0 M solution of sulfuric acid.

Chapter 8 | Slide 36 of 55 Dilution Problems How many liters of 6.0 M NaOH would be used to prepare 1L of 1.5 M NaOH?

Chapter 8 | Slide 37 of 55 Colloidal Suspension Mixtures that contain dispersed particles that are _______________ in size between those of a true solution and those of an ordinary heterogeneous mixture Made up of two parts: –Dispersed phase (similar to the solute) –Dispersing medium (similar to the solvent) Examples: –Milk –Blood

Chapter 8 | Slide 38 of 55 Solutions →Fig A beam of light travels through a true solution without being scattered. This is not the case for a colloidal dispersion.

Chapter 8 | Slide 39 of 55 Colligative Properties Some physical properties of solutions depend on the number of particles dissolved in solution –Vapor Pressure Lowering The more particles dissolved in solution, the lower the vapor pressure of the solution. –Boiling Point Elevation The more particles dissolved in solution, the higher the boiling point of the solution. –Freezing Point Depression The more particles dissolved in solution, the lower the freezing point.

Chapter 8 | Slide 40 of 55 Determining the Number of Particles in a Solution For covalent solutes: –Number of particles in solution is proportional to the concentration of the solute in solution (covalent solutes do not dissociate into ions when they dissolve) For ionic solutes: –Number of particles in solution is proportional to the concentration of the solute in solution TIMES the number of ions in the compound (ionic solutes dissociate into ions when they dissolve; for every NaCl that dissolves in water, you get 2 particles: an Na + and a Cl - )

Chapter 8 | Slide 41 of 55 How Many Particles Are in These Solutions? Solute MMoles of Particles in 1 L Solution Glucose, C 6 H 12 O M Sucrose, C 12 H 22 O M FeI M KF0.50 M

Chapter 8 | Slide 42 of 55 Which of the Following Solutions Has the Highest Boiling Point? a) M CaCl 2 b) M Na(OH) c) M K 2 (SO 4 ) d) M Al 2 (SO 4 ) 3 e) M CH 3 OH

Chapter 8 | Slide 43 of 55 Solutions Fig Close-ups of the surface of a liquid solvent before and after solute has been added.

Chapter 8 | Slide 44 of 55 Osmosis and Osmotic Pressure Osmosis –The passage of a solvent through a _______________ membrane separating a dilute solution (or pure solvent) from a more concentrated solution Semipermeable membrane –A membrane that allows certain types of molecules to pass through it but prohibits the passage of other types of molecules (usually based on the size of the particles)

Chapter 8 | Slide 45 of 55 Solutions Fig (a) Osmosis can be observed with this apparatus. (b) The liquid level in the tube rises until equilibrium is reached.

Chapter 8 | Slide 46 of 55 Solutions Fig Enlarged views of a semi-permeable membrane separating (a) pure water and a salt-water solution, and (b) a dilute salt-water solution.

Chapter 8 | Slide 47 of 55 Osmotic Pressure A colligative property –Increases with the number of particles in solution Osmolarity –The product of a solution’s molarity and the number of particles produced per formula unit if the solute dissociates –M x i

Chapter 8 | Slide 48 of 55 Solutions →Fig Osmotic pressure is the amount of pressure needed to prevent the solution in the tube from rising as a result of the process of osmosis.

Chapter 8 | Slide 49 of 55 Differences in Osmotic Pressure Regulate Solvent Flow Solvent will flow from the solution with ________ osmotic pressure (concentration of solute) to the solution with __________ osmotic pressure (concentration of solute) –Isotonic Solution A solution with an osmotic pressure that is equal to that within cells –Hypertonic Solution A solution with a higher osmotic pressure than that within cells –Hypotonic Solution A solution with a lower osmotic pressure than that within cells

Chapter 8 | Slide 50 of 55 Red Blood Cells and Differences in Solution Concentrations Normal red blood cell in an isotonic solution Red blood cell in a hypotonic solution: swelling and hemolysis occur Red blood cell in a hypertonic solution: shrivelling and crenation occur

Chapter 8 | Slide 51 of 55 Effects of Osmosis

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Chapter 8 | Slide 54 of 55 Solutions Fig In dialysis, there is a net movement of ions from a region of higher concentration to a region of lower concentration.

Chapter 8 | Slide 55 of 55 Solutions →Fig Impurities can be removed from a colloidal dispersion by using a dialysis procedure.

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