1. Solutions!

2. Classification of Matter Matter Pure Substanc es Mixtures HomogeneousMixturesHeterogeneousMixturesElementsCompounds

3. Heterogeneous Mixtures See visibly different regionsSee visibly different regions –Granite –Dirt –Cereals –Oil & Vinegar See a boundarySee a boundary –Ice cube in water

4. Homogeneous Mixtures Particles very small – on atomic scaleParticles very small – on atomic scale –Can’t see particles –Can’t sort particles –Can’t get trapped by filter –Can’t scatter light Particles evenly distributedParticles evenly distributed Particles do not separateParticles do not separate

5. CuSO 4 (aq) Which is a solution & how do you know?

6. Solution Homogeneous mixture of 2 or more substances in a single physical state (phase)

7. Parts of a Solution SoluteSolute = dissolved substance SolventSolvent = dispersing medium

8. Identify the solute and solvent in each picture

9. Solute = ? Solvent = ?

10. Hints to identify solute & solvent SoluteSolute: changes phase = substance have less of SolvenSolvent: maintains phase = substance have most of

11. Aqueous Solutions WaterWater is solvent Transition metalsTransition metals form brightly colored solutions

12. Solutions occur in all 3 phases! Alloys: Brass, etc. SolidSolid Fillings: Hg in Ag SolidLiquid H 2 in Pd metal SolidGas Salt water LiquidSolid Antifreeze in radiator LiquidLiquid Seltzer Water LiquidGas MothballsGasSolid Water Vapor in Air GasLiquid AirGasGas ExampleSolventSolute

13. Gas dissolved in a solid

14. CO 2 in and out of water Bubbles mean it’s a mixture not a solution!

15. Alloys

16. Soluble Soluble Soluble – capable of being dissolved soluble A substance that dissolves in another substance is soluble in that substance

17. Insoluble A substance that does not dissolve in another substance

18. Amounts that can dissolve SolubilitySolubility = maximum amount of substance that will dissolve in given amount of another substance LIMITSLIMITS to amounts of most liquid/solid solutes that will dissolve in given solvent TemperaturepressureTemperature and pressure affect solubility

19. Factors that affect the rate of dissolving Rate of dissolving is different from amount that will dissolve!Rate of dissolving is different from amount that will dissolve! Rate is how fastRate is how fast –factors influence rate of dissolving: TemperatureTemperature Stirring or AgitationStirring or Agitation Surface Area of SoluteSurface Area of Solute Amount of solute already dissolvedAmount of solute already dissolved

20. Dissolving Dissolving is physical changeDissolving is physical change All physical & chemical changes are accompanied by changes in energyAll physical & chemical changes are accompanied by changes in energy

21. Equations for Dissolving C 6 H 12 O 6 (s) + H 2 O(l)  C 6 H 12 O 6 (aq) NaCl(s)+H 2 O(l)  Na +1 (aq) + Cl -1 (aq)

22. source Covalent substances dissolve to produce molecules in solution

23. Ionic substances dissolve to produce ions in solution

24. Solvation Interaction between solvent molecules and solute particlesInteraction between solvent molecules and solute particles –Solute particles surrounded by solvent particles in dissolving process Solute particles may be ions, polar molecules, or nonpolar moleculesSolute particles may be ions, polar molecules, or nonpolar molecules Solvent molecules may be polar or nonpolarSolvent molecules may be polar or nonpolar

25. Hydration Specific name for solvent-solute interaction when solvent is water

26. Hydration of chloride ion Also called: molecule-ion interaction

27. Solute-solvent interaction must be greater than: interaction between interaction between solute particles solute particles for dissolving to occur for dissolving to occur Molecule-ion interaction

28. Solvation in different systems.

29. Solubility Amount solute that will dissolve in specific solvent at given TEMPERATURE and PRESSUREAmount solute that will dissolve in specific solvent at given TEMPERATURE and PRESSURE Amount can be determined experimentallyAmount can be determined experimentally Units:Units: grams solute per 100 grams solvent grams solute per 100 grams solvent

30. Solubility Curves of Selected SOLIDS Solubility traces for most but not all solids have (+)’ve slopes; The hotter the solvent, the more solute dissolves

31. Solubility Curves of Selected GASES Solubility traces for all gases have (–)’ve slopes Why do fish like cold water?

32. Why do you see bubbles form on the side of the beaker as the water warms up? (Note: it’s not hot enough to boil)

33. Vocabulary Interlude MiscibleMiscible: two liquids that WILL MIX together in any amounts –Water and ethanol are miscible in all proportions ImmiscibleImmiscible: Liquids that will NOT MIX –Oil and water are immiscible

34. Oil & H 2 O are immiscible

35. Types of Solutions Matter Pure Substances Mixtures Homogeneous Mixtures = Solutions Heterogeneous Mixtures ElementsCompounds Conduct current Nonconductor

36. Electricity What do you need to conduct electricity?What do you need to conduct electricity? Mobile, charged particles!!!!

37. Vocabulary Interlude ElectrolyteElectrolyte: substance that dissolves in water to form solution that conducts electricity ions in solution NonelectrolyteNonelectrolyte: substance that dissolves in water to form solution that does not conduct electricity neutral molecules in solution

38. Electrolyte vs. Nonelectrolyte Which solution conducts a current?

39. Dilute vs. Concentrated Tells relative amount of solute in solvent ConcentratedConcentrated –large amounts of solute DiluteDilute –small amounts of solute

40. Which solution is most dilute? The most concentrated? How do you know? The stronger the color, the more concentrated the solution

42. Which solution is more concentrated? More dilute? of solute particles What can you say about the # of solute particles in pictures b and c? It’s the same!

43. Unsaturated Solution Less Less solute than maximum amount that will dissolve at given temperature and pressure

44. Saturated Solution No more solute will dissolve at given temperature & pressureNo more solute will dissolve at given temperature & pressure Solubility = amount of solute required to form a saturated solutionSolubility = amount of solute required to form a saturated solution

45. The solution is saturated when the solute stops dissolving

46. Dynamic Equilibrium = Saturated Solution Microscopic level: Rate of dissolving = Rate of recrystallization No apparent change Macroscopic level: No apparent change

47. Supersaturated Solution moreContains more solute than saturated solution –VERY unstable –have to be clever to make these (need to use heat)

48. Testing for saturation: Toss crystal of solute into solution and see what happens

49. 3 possible results: Crystal dissolves:Crystal dissolves: Crystal sinks to bottom of solution:Crystal sinks to bottom of solution: Bam! Suddenly have lots of solid solute in beaker:Bam! Suddenly have lots of solid solute in beaker: Unsaturated solution Saturated solution Supersaturated solution

50. What kind of solution was this?

51. How do terms saturated, unsaturated & supersaturated fit in with the solubility curves? Saturated solutions have maximum solute that will dissolve at given temperature –Any point on trace lines represent saturated solutions All points above trace lines represent supersaturated solutions All points below trace lines represent unsaturated solutions

52. AA BB CC DD Characterize points A, B, C, D with respect to the KNO 3 trace using the terms dilute & concentrated, saturated, unsaturated, or supersaturated A,C = concentrated & supersaturated B,D = dilute & unsaturated

53. Summary of Dissolving Occurs at surface of solidOccurs at surface of solid Involves interaction between solute and solventInvolves interaction between solute and solvent Interaction is called “solvation”Interaction is called “solvation” –If water is solvent, interaction is called “hydration” Involves changes in energyInvolves changes in energy

55. Solubility Information Often presented in graphs Graph show number grams of substance that can dissolve in water between 0 o C and 100 o C Trace line represents saturated solution –above trace line represents supersaturated solutions –below trace line represents unsaturated solutions

56. Solubility Graphs Traces: have positive or negative slopes Most solidsMost solids have positive slope –the hotter the water, the more solute dissolves –The colder the water, the less solute dissolves All gasesAll gases have negative slope –the hotter the water, the less gas dissolves –The colder the water, the more gas dissolves