You think you have problems; well we have SOLUTIONS!

1. You think you have problems; well we have SOLUTIONS! UNIT 7 SOLUTIONS

2. Why does a raw egg swell or shrink when placed in different solutions?

3. Pages 466-486 Notes One Unit Seven Vocab, vocab, vocab! Types of Mixtures and Solutions Factors affecting solubility Complete W701 & A701

4. Important Vocabulary • Solutions are simply a homogenous mixture • Homogenous: same throughout • Ex: Water + Sugar, Air • Heterogeneous: different throughout • Ex: Oil+ Water • Solutions= Solute + Solvent • Solute- • Things that get dissolved • Solvent- • Things into which solute is dissolved • Determines the state of solution • Largest component

5. Common Mixtures SOLUTE EXAMPLE SOLVENT Type liquid mayonnaise liquid emulsion gas whipped cream liquid liquid foam solid dust in air gas aerosol liquid hair spray gas aerosol solid ruby glass solid solid liquid pearl solid emulsion gas Styrofoam solid solid foam

6. Solution Types SOLUTE EXAMPLE SOLVENT PHASE gas a i r gas gas gas soda pop liquid liquid liquid antifreeze liquid liquid liquid filling solid solid solid seawater liquid liquid solid brass solid solid

7. How does a solution form? • As a solution forms, the solvent pulls solute particles apart and surrounds, or solvates, them. Factors that affect solvation: 1. Agitation (stirring) 2. Decreasing particle size (grinding up solute) 3. Heating

8. Key Difference Solvation Solubility Process of dissolving Rate of dissolving- HOW FAST The amount of solute that can be dissolved in a given amount of solvent Amount that can be dissolved-HOW MUCH RATE of dissolving is not the same as the AMOUNT that can be dissolved

9. Factors Affecting Solubility • 1. Nature of Solute / Solvent. • 2. Temperature Increase • i) Solid/Liquid • ii) gas • 3. Pressure Factor - • i) Solids/Liquids - Very little • ii) gas • iii) squeezes gas into solution.

10. Nature of Solute/Solvent Like Dissolves Like • Non-polar in Non-polar • Butter in Oil • Non-polar in polar • Oil in H2O • Polar in Polar • C2H5OH in H2O • Ionic compounds in polar solvents • NaCl in H2O

11. At Higher Temperatures…. • Gases become less soluble in water • Ex: Boiling water. The first bubbles that appear when tap water is heated are bubbles of air released as the increasing temperature reduces the solubility of air in water. • Most ionic solids become more soluble in water

12. Solubility of solids Changes with Temperature 200 • How does the solubility Δ with temperature? • How many grams of potassium chromate will dissolve in100g water at 70oC? • 70g • How many grams of lead(II) nitrate will precipitate from 250g water cooling from 70oC to 50oC? 180 solids gases 160 140 grams solute /100g H2O 120 101g Pb(NO3)2 100 82g 80 K2CrO4 60 40 250g 20 _____ 19gx =48g 100g 20 30 40 50 60 70 80 90 100 Temperature 0C

13. Solubility of Gases Changes with Temperature • a) Why are fish stressed, if the temperature of the water increases? • How much does the solubility of oxygen change, for a 20oC to 60oC change? • 1.00-0.60=0.40mg 5.0 4.5 4.0 3.5 3.0 milligrams solute /100g H2O 2.5 2.0 1.5 1.00mg N2 1.0 O2 0.60mg 0.5 0 10 20 30 40 50 60 70 Temperature 0C

14. Pressure Factor • Pressure change has little effect on the solubility of a liquid or solid in water, but the solubility of a gas is very much affected by pressure Greater pressure… more dissolved gas

15. Summary • Solutions are a homogenous mixture • Solutions are made up of solutes and solvents • Solubility refers to the how well solutes dissolve in solvents • Solvation refers to the process of dissolving • Agitation, heating, and decreasing particle size affect the rate of solvation • Factors that affect solubility: • Nature of solvents • Temperature • Pressure

16. Why does a raw egg swell or shrink when placed in different solutions?

17. An egg soaking in vinegar with part of it’s shell dissolved. A dehydrated naked egg side-by-side with a brilliant red naked egg soaked in red food coloring. A naked egg that was soaked in corn syrup for a few days. Much of the water inside the egg has moved out through the membrane.

18. Pages 466-486 Notes Two Unit Seven Characteristics of solutions Kool-Aid example Molarity and Molality Complete A702 & A702B

19. More Vocab! • Solutions can be classified as saturated or unsaturated. • Saturated: Max amount of solute dissolved in solvent • Unsaturated: Less than the maximum amount of solute dissolved in solvent

20. More, more, more! • Supersaturated solutions contain more solute than is possible to be dissolved. • Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways: • Warm the solvent so that it will dissolve more, then cool the solution • Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

21. Characteristics of Solutions

22. Solutions can also be described as Concentrated • This means that there is a lot of solute dissolved per amount of solvent. Dilute • This means that there is relatively little solute dissolved per amount of solvent.

23. Making Kool-Aid • When you make Kool-Aid, what is the solute? • What is the solvent? • What is the solution?

24. Making Kool-Aid • If you make a concentrated solution of Kool-Aid. • This solution has too much___________. • If you make a dilute solution of Kool-Aid. • This solution has too much ____________. • How can we use the concentrated solution of Kool-Aid to make a more dilute solution of Kool-Aid? solute solvent

25. Saturated Solutions • Is there a limit to how much Kool-Aid or sugar we can dissolve in water? • What happens when we reach that limit? • What can we do to the solution to make more sugar dissolve? • When we can add no more solute to a solution, the solution is SATURATED.

26. How do we measure concentration? • M=mol/L • mol=MxL • L=mol/M

27. Finding Molarity from Mass and Volume What is the concentration (M) of a solution with a volume of 600. mLthat contains 25.5 g of ammonia? 1. Calculate the Chart Mass of ammonia : Element # Mass 2. Calculate the moles of the solute (NH3) N 1X 14.0 g/mol = 14.0 g/mol H 3X 1.0 g/mol = 3.0 g/mol 17.0 g/mol 25.5 g 1 mol = 1.50 mol 17.0 g 3. Calculate the Moles/Liters Ratio 1.50mol / 0.600L M = M = 2.52 mol/L

28. Finding Volume from Molarity and Mass How many milliliters of 2.50M solution can be made using 25.5grams of NH3? • 1)Calculate chart mass: • 2)Calculate the moles of solute: • 3)Calculate Volume: • V= Mass E # 14.0 N 1x 14.0 = 3.0 H 3x 1.0 = 17.0g/m 25.5g ÷ 17.0g/mol= 1.50m V=mol/M V= (1.50m) / (2.50M) 0.600L solution 600. mL

29. Finding Mass from Molarity and Volume • How many grams of NH3 are in 600. mL solution at 2.50M? • 1) Calculate chart mass: • 2) Calculate moles • mol=1.50m • 3) Calculate mass • g=25.5g NH3 Mass E # 14.0 N 1x 14.0 = 3.0 H 3x 1.0 = 17.0g/m g ÷ cm= mol mol = M x L mol= 2.50M x 0.600L g = x mol cm x g= (17.0g/m) (1.50m)

30. We also measure concentration with Molality (m) • Is defined as : MOLES OF SOLUTE Kg of SOLVENT

31. Molality, what? • Why in the world would we have a separate way of expressing concentration, the equation for which looks so similar to the molarity equation? • The answer lies in the denominator of that equation. Molality does not change with temperature of the solution. While volume of a solution can change with temperature due to expansion or contraction, the mass of the solvent will not change with temperature.

32. Finding Molality from Mass What is the molality (m) of a solution that has 18.7 grams of magnesium sulfate in 550 grams of water? 1. Calculate the Chart Mass of magnesium sulfate Element # Mass (MgSO4) Mg 1X 24.3 g/mol = 24.3g/mol 3. Convert grams to kilograms S 1X 32.0 g/mol = 32.0 g/mol O 4X 16.0 g/mol = 64.0 g/mol 550 g .001 kg 120.3 g/mol 2. Calculate the moles of the solute 1 g 18.7 g 1 mol = .921 mol = .55 kg 120.3 g 4. Calculate Molality (m) m= .921 mol/ .55 kg= 1.67 mol/kg

33. UNITS OF CONCENTRATION • Molarity, M, moles solute per liter solution • Molality, m, moles of solute per kilogram solvent • Mole fraction, XA, moles A divided by moles total • Weight percent (mass percent), wt.% A, (mass A divided by mass total) x 100% • parts per million, ppm, is calculated like percent, but multiply by 106

34. Summary Solutions can be characterized as: • Saturated: Max amount of solute dissolved in solvent • Unsaturated: Less than the maximum amount of solute dissolved in solvent • Supersaturated solutions contain more solute than is possible to be dissolved. • Concentrated: This means that there is a lot of solute dissolved per amount of solvent. • Dilute: This means that there is relatively little solute dissolved per amount of solvent. We measure concentration by calculating molarity and molality.

35. Notes Three Unit Seven Dilutions Complete L701 Compete D701 Flint articles

36. Dilutions • Relatively little solute dissolved per amount of solvent. • We care about dilutions because sometimes it is necessary to prepare a solution from an existing solution • Solution of NaCl vs solution of HCl(aq) • Use this formula to determine how to dilute a stock solution to the desired concentration: M1V1 = M2V2

37. Dilutions Lab • Purpose: To perform a serial dilution using a solution of the ionic compound potassium permanganate (KMnO4).

38. Notes Four Unit Seven Colligative Properties Vapor Pressure Boiling and Freezing Point BP Elevation and Freezing FP Depression Calculating Freezing Point Depression Mass

39. How do you get from this…

40. …to this?

41. Add an ionic compound!

42. Colligative Properties How solutes affect the properties of solutions

43. Colligative Properties On adding a solute to a solvent, the properties of the solvent are modified. • Vapor pressure decreases (lowering) • Boiling point increases (elevates) • Freezing point decreases (depression) These changes are called COLLIGATIVE PROPERTIES. They depend only on the NUMBER of solute particles relative to solvent particles, not on the KINDof solute particles.

44. How does a solution form? • As a solution forms, the solvent pulls solute particles apart and surrounds, or solvates, them. A complicated game of red rover Water molecules are hydrogen bonded to each other A solute interrupts that attraction

45. Vapor Pressure Lowering • The particles of solute are surrounded by and attracted to particles of solvent. • Now the solvent particles have less kinetic energy and tend less to escape into the space above the liquid. • So the vapor pressure is less.

46. Why does vapor pressure of the solvent decrease?

47. Boiling Point Elevation and Freezing Point Depression Solute-solvent interactions also cause solutions to have higher boiling points and lower freezing points than the pure solvent.

48. Effect on Freezing Point The addition of a solute to a solvent causes the freezing point of the solution to decrease.

49. Car Radiators & antifreeze Antifreeze is added to a car’s cooling system to keep it from freezing and damaging the engine when the temperature falls below freezing.

50. Definition of Boiling Point The temperature at which the vapor pressure of a liquid becomes equal to the pressure above the liquid.