Chapter 7: Properties of Solutions

Mixture Review  Mixtures are combos of elements and/or compounds that are physically combined  True mixtures can be separated by physical means that do not break or form bonds  Mixtures do not exist in a fixed ratio by mass  Mixtures are combos of elements and/or compounds that are physically combined  True mixtures can be separated by physical means that do not break or form bonds  Mixtures do not exist in a fixed ratio by mass

Classifying mixtures  Heterogeneous mixtures: different phases (states of matter), non-uniform, no consistent makeup throughout a sample  Homogeneous mixture: same phase (state of matter), uniform, with a consistent makeup throughout a sample  Heterogeneous mixtures: different phases (states of matter), non-uniform, no consistent makeup throughout a sample  Homogeneous mixture: same phase (state of matter), uniform, with a consistent makeup throughout a sample

How can we separate mixtures?  We can separate by physical properties:  Density  Molecular polarity  Freezing point  Boiling point  We can separate by physical properties:  Density  Molecular polarity  Freezing point  Boiling point

Techniques for separating heterogeneous mixtures  Pouring off: a separatory funnel is used with non- mixing liquids (different polarities or densities)  Filtration: small particles pass through while larger particles are trapped  Filtrate is what is collected in the filter  Pouring off: a separatory funnel is used with non- mixing liquids (different polarities or densities)  Filtration: small particles pass through while larger particles are trapped  Filtrate is what is collected in the filter

Distillation  Used to separate homogeneous mixtures by boiling points  One part boils off, vapor gets cooled and trapped in a separate container  Used to separate homogeneous mixtures by boiling points  One part boils off, vapor gets cooled and trapped in a separate container

Separation  Particle size: manually separate parts of a mixture based on size  Magnetic separation: remove metallic elements from non- metallic (iron and sulfur)  Particle size: manually separate parts of a mixture based on size  Magnetic separation: remove metallic elements from non- metallic (iron and sulfur)

Chromatography  Separation by attraction

Review Can mixtures be separated by physical means? Do mixtures exist as fixed ratios? How many phases are there in a homogenous mixture? When would you use filtration? When would you use distillation? Describe a procedure that could be used to separate a mixture of sand and table salt. Can mixtures be separated by physical means? Do mixtures exist as fixed ratios? How many phases are there in a homogenous mixture? When would you use filtration? When would you use distillation? Describe a procedure that could be used to separate a mixture of sand and table salt.

Aim: How can we describe solutions?  Do Now: Complete mixtures questions on handout, if not done already  Look up definitions for vocabulary page  Do Now: Complete mixtures questions on handout, if not done already  Look up definitions for vocabulary page

Solutions (homogeneous mixtures)  Can’t be filtered (extremely small dissolved particles)  Dissolved particles never settle, except when caused by temperature changes or evaporation  Liquid & gas solutions are clear and transparent since dissolved particles can’t be seen  Single phase, even when starting with components of different phases  Can’t be filtered (extremely small dissolved particles)  Dissolved particles never settle, except when caused by temperature changes or evaporation  Liquid & gas solutions are clear and transparent since dissolved particles can’t be seen  Single phase, even when starting with components of different phases

Parts of a Solution  The solute is the dissolved substance, the smaller portion of the solution  The solvent is the substance in which the solute is dissolved, the larger portion of the solution Solute + Solvent = Solution  The solute is the dissolved substance, the smaller portion of the solution  The solvent is the substance in which the solute is dissolved, the larger portion of the solution Solute + Solvent = Solution

Solute & Solvent  10g of NaCl in 100mL of water  5mL of CO 2 (g) and 20mL O 2 (g) in 80mL N 2 (g)  3g of carbon in 97g of iron  10g of NaCl in 100mL of water  5mL of CO 2 (g) and 20mL O 2 (g) in 80mL N 2 (g)  3g of carbon in 97g of iron

Types of Solutions  Gas solutions (air): gases completely dissolved in one another  Liquid solutions: solid, liquid, or gas solutes dissolved in a liquid solvent  Carbonated water (CO 2 gas in water)  Salt water (solid salt in water)  Antifreeze (liquid ethylene glycol in water)  Solid solution: mostly solid dissolved in solid, but can be a liquid or gas dissolved in a solid  Alloys of bronze (Cu/Sn) or steel (Fe/C)  Gas solutions (air): gases completely dissolved in one another  Liquid solutions: solid, liquid, or gas solutes dissolved in a liquid solvent  Carbonated water (CO 2 gas in water)  Salt water (solid salt in water)  Antifreeze (liquid ethylene glycol in water)  Solid solution: mostly solid dissolved in solid, but can be a liquid or gas dissolved in a solid  Alloys of bronze (Cu/Sn) or steel (Fe/C)

Aqueous Solutions  Aqueous solutions are solutions in which water is the solvent  Given the abbreviation (aq)  Ionic compounds break into their oppositely charged parts when they enter aqueous solutions NaCl (s)  Na+ (aq) + Cl- (aq)

Aqueous Solution Examples  Tea (aq)  NaCl (aq)  Ammonia: NH 3 (aq)  Hydrochloric acid: HCl (aq)  Sodium hydroxide: NaOH (aq)  Tea (aq)  NaCl (aq)  Ammonia: NH 3 (aq)  Hydrochloric acid: HCl (aq)  Sodium hydroxide: NaOH (aq)

How Can We Describe Mixtures?  Homogeneous mixtures (solutions)  Miscible: capable of being mixed  One substance dissolves in another  Homogeneous mixtures (solutions)  Miscible: capable of being mixed  One substance dissolves in another  Heterogeneous mixtures  Immiscible: not capable of mixing  Do not dissolve in one another

Saturated Solutions are in Equilibrium  Solutes dissolve in solvents, but only to a certain point  Solutions with the maximum amount of dissolved solute are saturated solutions  Saturated solutions are in a balanced state of equilibrium  Solutes dissolve in solvents, but only to a certain point  Solutions with the maximum amount of dissolved solute are saturated solutions  Saturated solutions are in a balanced state of equilibrium

Any extra solid that cannot be dissolved falls out of the solution and crystallizes as a precipitate

In saturated solutions, the system is at equilibrium. The rate of dissolution is equal to the rate of crystallization.

Explaining Molecule-Ion Forces of Attraction in Solution  When ionic compounds mix with water, they form aqueous solutions of dissolved ions  Polar water molecules attract the ions, separating them and dissolving the solid  This is molecule-ion attraction  When ionic compounds mix with water, they form aqueous solutions of dissolved ions  Polar water molecules attract the ions, separating them and dissolving the solid  This is molecule-ion attraction

Explaining Molecule-Ion Forces of Attraction in Solution re=related 6X0&feature=related re=related 6X0&feature=related

Conclusion Questions  Answer the following questions on paper:  How many phases are there in a homogeneous mixture?  How are substances different from solutions?  How does a solute differ from a solvent in the formation of a solution?  What happens to solute and solvent when ionic compounds like NaCl dissolve in H 2 O?  Answer the following questions on paper:  How many phases are there in a homogeneous mixture?  How are substances different from solutions?  How does a solute differ from a solvent in the formation of a solution?  What happens to solute and solvent when ionic compounds like NaCl dissolve in H 2 O?

How Do You Like Your Tea?  Do Now: Take out notes and Reference Tables  Consider what makes the three cups of iced tea on the front desk different  Do Now: Take out notes and Reference Tables  Consider what makes the three cups of iced tea on the front desk different

For Tuesday Trimester Test  Period 3: in this room  Periods 5/6: in this room  Period 9: in Physics room downstairs  HW: print packets from website, finish vocab sheet, hand in labs  Period 3: in this room  Periods 5/6: in this room  Period 9: in Physics room downstairs  HW: print packets from website, finish vocab sheet, hand in labs

Describing Types of Solutions: Unsaturated Solutions  Unsaturated solutions have less than the maximum amount of solute dissolved in them  More solute can still be added and dissolved  Dilute solutions: solute-SOLVENT  100 seat restaurant with only 40 people seated  Unsaturated solutions have less than the maximum amount of solute dissolved in them  More solute can still be added and dissolved  Dilute solutions: solute-SOLVENT  100 seat restaurant with only 40 people seated

Describing Types of Solutions: Saturated Solutions  Saturated solutions have the maximum amount of solute dissolved in them  No more solute can be dissolved in saturated solutions  Concentrated solutions: SOLUTE-solvent  100 seat restaurant with 100 people seated in it  Saturated solutions have the maximum amount of solute dissolved in them  No more solute can be dissolved in saturated solutions  Concentrated solutions: SOLUTE-solvent  100 seat restaurant with 100 people seated in it

Describing Types of Solutions: Supersaturated Solutions  Supersaturated solutions have more than the theoretical maximum amount of solute dissolved in them  Rare and unstable, need high temp/pressure  SOLUTE >>> solvent, excess solute will precipitate if solution is agitated  100 seat restaurant with 120 people in it, then fire marshal comes and throws 20 people out  Supersaturated solutions have more than the theoretical maximum amount of solute dissolved in them  Rare and unstable, need high temp/pressure  SOLUTE >>> solvent, excess solute will precipitate if solution is agitated  100 seat restaurant with 120 people in it, then fire marshal comes and throws 20 people out

Rock Candy

Supersaturation video

Solubility  If a substance is soluble, it can be dissolved in a solvent  Solubility is how much of a solute will dissolve in a certain amount of solvent at a given temperature  If a substance is soluble, it can be dissolved in a solvent  Solubility is how much of a solute will dissolve in a certain amount of solvent at a given temperature

How Can We Describe Solutions?  Easy answer: use reference Table G  Up curves are solids  Direct relationship   temp,  solubility  Down curves are gases  Indirect relationship   temp,  solubility  Easy answer: use reference Table G  Up curves are solids  Direct relationship   temp,  solubility  Down curves are gases  Indirect relationship   temp,  solubility

Understanding Solubility Curves  Each line represents a saturated solution of a solute, across a range of temperatures  The higher the point on a line, the more soluble a substance is  Experiments tell us how much solute can be dissolved in 100g of water at a given temp  Each line represents a saturated solution of a solute, across a range of temperatures  The higher the point on a line, the more soluble a substance is  Experiments tell us how much solute can be dissolved in 100g of water at a given temp

 Remember: points on lines are saturated solutions (at equilibrium). Rate of dissolution = rate of crystallization  Remember: points on lines are saturated solutions (at equilibrium). Rate of dissolution = rate of crystallization

Conclusion  Which type of solution can still hold additional solute?  Which type of solution holds the most solute possible?  What must be done to a solution to make it supersaturated?  Which type of solution is represented by any point on a solubility curve?  Which type of solution can still hold additional solute?  Which type of solution holds the most solute possible?  What must be done to a solution to make it supersaturated?  Which type of solution is represented by any point on a solubility curve?

Homework  Complete review book questions, on separate paper  Page 123, #  Complete review book questions, on separate paper  Page 123, # 13-23