1. Quick Review Classification of Matter Physical/Chemical Prop. Physical/Chemical Changes Intensive/Extensive Soluble vs Miscible

2. Slightly-less Quick Review Solution Terms and Types

3. A ____________ is a homogenous mixture of two or more substances The ____________ is(are) the substance(s) present in the smaller amount(s) The ____________ is the substance present in the larger amount Types of Solutions

4. A solution is a homogenous mixture of two or more substances The solute is(are) the substance(s) present in the smaller amount(s) The solvent is the substance present in the larger amount Types of Solutions

5. A ______________ ______________ contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature. An ______________ ______________ contains less solute than the solvent has the capacity to dissolve. A ______________ ______________ contains more solute than is present in a saturated solution. Sodium acetate crystals rapidly form when a seed crystal is added to a supersaturated solution of sodium acetate.

6. A saturated solution contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature. An unsaturated solution contains less solute than the solvent has the capacity to dissolve. A supersaturated solution contains more solute than is present in a saturated solution. Sodium acetate crystals rapidly form when a seed crystal is added to a supersaturated solution of sodium acetate.

7. Solution Math Review

8. Concentration Units Continued M = moles of solute liters of solution Molarity Molality m = moles of solute mass of solvent (kg) Dilution: M 1 V 1 = M 2 V 2 S1P1S1P1 = S2P2S2P2 Henry’s Law:

9. Review 1) Explain how you would prepare 500. mL of a 0.33 M solution of sodium chloride. 2) Determine the molal concentration of a solution in which 320. grams of glucose C 6 H 12 O 6 are dissolved in 4000 grams of water. 3) If the solubility of Carbon Dioxide in water is.625g/L at 790. Torr and 25.0 degrees Celsius; what would be the solubility at constant temperature and 3.00 atm? 4) If water and ethanol mix in all proportions they are said to be? If however water and oil don’t mix at any proportion they are said to be?

10. Solubility (The whole truth this time)

11. Full disclosure: While we do have PLENTY to cover….and I really hate adding more to it… The IB exams will not expect much from in terms of enthalpy of solution. I’m still going to cover it because I think it will be helpful background for upcoming material. Also note the lack of colligative properties….

12. “Like dissolves like” Two substances with similar intermolecular forces are likely to be soluble in each other. non-polar molecules are soluble in non-polar solvents CCl 4 in C 6 H 6 polar molecules are soluble in polar solvents C 2 H 5 OH in H 2 O ionic compounds are more soluble in polar solvents NaCl in H 2 O or NH 3 (l) oil (non-polar) and water (polar) don’t mix

13. Enthalpy of Solution Enthalpy is the sum of internal energy in a substance However, commonly (and confusingly) it is most often used in terms of enthalpy CHANGE (energy leaving or entering the substance in the form of heat.) Enthalpy of Solution refers to the overall amount of heat absorbed/released in the process of dissolving (exothermic/endothermic) MOST BEFUDDLING: – A substance getting cooler – A substance absorbing energy – An endothermic process Results in a POSITVE enthalpy change. (Because enthalpy is in terms of the substances energy)

14. Three types of interactions in the solution process: solvent-solvent interaction solute-solute interaction solvent-solute interaction  H soln =  H 1 +  H 2 +  H 3 Solute molecules separate. This is an endothermic process because energy is required for this reaction, so ΔH1 > 0. (Positive) Also needs to overcome the intermolecular forces holding it together. Like the first step, this reaction is an endothermic one and ΔH2 > 0 (Positive) because energy is required to break the forces between the molecules. The separated solute molecules and the separated solvent molecules join together to form a solution. This is an exothermic reaction, because energy is given off as the two substances bond together; therefore, ΔH3 < 0. (Negative)

15. SOLUBILITY Rule of thumb?Why? Explained by energies of solution formation. 3 parts to solution formation: Breaking up (expanding) the solute ∆H 1 positive and higher for polar/ionic Overcoming the intermolecular forces in (expanding) the solvent ∆H 2 Also + and higher for polar/ionic Solvent and solute interaction to form solution ∆H 3 Negative ∆H soln =∆H 1 + ∆H 2 +∆H 3 Enthalpy (heat) of solutionLattice Enthalpy (Of Solute H 1 and Solvent H 2 separation) Heat of Solvation Illustrations Oil in water; NaCl in water; I 2 in hexane

16. Examples 1. If ΔHsolution = 230 J/mol, ΔH2 = 108 J/mol, and ΔH3 = - 47 J/mol, what is the value of ?H1? ΔHsolution = ΔH1 + ΔH2 + ΔH3 230 J/mol = ΔH1 + 108 J/mol + - 47 J/mol ΔH1 = 230 J/mol - 108 J/mol +47 J/mol ΔH1 = 169 J/mol 2. If ΔHsolution = -219 J/mol, is the solution ideal or nonideal? Solution is only ideal when ΔHsolution = 0 -219 J/mol does not equal 0 Therefore, the solution is non-ideal.

17. The dreaded ENERGY DIAGRAM The following cycle is for calcium chloride, and includes a lattice dissociation enthalpy of +2258 kJ mol-1. We have to use double the hydration enthalpy of the chloride ion because we are hydrating 2 moles of chloride ions. So... ΔHsol = +2258 - 1650 + 2(-364) ΔHsol = -120 kJ mol-1

18. Identify which in each pair would be most soluble in water: hexane or ethanol Ethanol or octanol ↑ temperature generally increases solubility for solid in liquid ↑ pressure increases solubility of gas in liquid When does solubility of a solid not increase with temp?

19. Summary So…To over simplify it: Solubility of a solute increases with increasing similarity to it’s solvent (In terms of IMF’s and THEN size. So basically Like-dissolves-like UNLESS the solute molecule is huge (and thus the London-Dispersion Forces require too much energy to break) NOTE: MOST “SOLID DISSOLVING” SOLUTION FORMATION IS ENDOTHERMIC +∆H What about “Gas dissolving solution formation?

20. Solution Math

21. Concentration Units The concentration of a solution is the amount of solute present in a given quantity of solvent or solution. Weight or Mass percent % by mass = x 100% mass of solute mass of solute + mass of solvent = x 100% mass of solute mass of solution Mole Fraction X A = moles of A sum of moles of all components

22. SOLUTIONS Solution Composition [concentration] Mass % - mass solute x 100 mass solution Mole fraction of A = n A = χ A n A + n B Molality = mol solute kg solvent Molarity = L solution Normality = # equivalents L solution For acid-base, 1 eq = mass of A or B which produces 1 mol of H + or OH -. For redox 1 eq = quantity of oxid or red agent which will provide or accept 1 mol of e -.

23. SOLUTIONS What is the molality of a solution prepared by dissolving 18.3 g of cobalt(II) nitrate in 500. mL H 2 O? What is m for the ions? How would you prepare 250. mL of a 2.00 M solution of NaOH? What is the normality of a 0.500 M solution of HCl? H 2 SO 4 ?

24. Colligative Properties A dding a solute to a solvent affects the properties of the solvent. V apor pressure is depressed –R–R aoult’s Law: P A = P 0 A x (n A /n soln ) –D–D istillation B oiling Point is elevated F reezing point is depressed O smotic Pressure is elevated –O–O smosis *Osmosis is the spontaneous movement of solvent particles through a membrane towards a region of higher solute concentration. Tends to even out solute concentrations. *The osmotic pressure of a solution is the pressure difference needed to stop the flow of solvent across a semipermeable membrane * Raoult's law states that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature scaled by the mole fraction of the solvent present: (Because Solute particles block solvent from evaporating to a vapor, the initial vapor pressure is reduced by a factor of the mole fraction.)

25. Raoult's law states that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature scaled by the mole fraction of the solvent present: Or…Because Solute particles block solvent from evaporating to a vapor, the initial vapor pressure is reduced by a factor of the mole fraction. Raoult’s Law: P A = P 0 A x (n A /n soln ) Recall from Chem One: At any given temperature for a particular solid or liquid, there is a pressure at which the vapor formed above the substance is in dynamic equilibrium with its liquid or solid form. This is the vapor pressure of the substance at that temperature. At equilibrium, the rate at which the solid or liquid evaporates is equal to the rate that the gas is condensing back to its original form. All solids and liquids have a vapor pressure, and this pressure is constant regardless of how much of the substance is present.

26. Temperature and Solubility Solid solubility and temperature solubility increases with increasing temperature

27. Temperature and Solubility Solid solubility and temperature solubility decreases with increasing temperature

28. Fractional Crystalization is the separation of a mixture of substances into pure components on the basis of differing solubilities. Suppose you have 90 g KNO 3 contaminated with 10 g NaCl. Fractional crystallization: 1.Dissolve sample in 100 mL of water at 60 0 C 2.Cool solution to 0 0 C 3.All NaCl will stay in solution (s = 34.2g/100g) 4.78 g of PURE KNO 3 will precipitate (s = 12 g/100g). 90 g – 12 g = 78 g

29. Temperature and Solubility Gas solubility and temperature solubility usually decreases with increasing temperature

30. Pressure and Solubility of Gases The solubility of a gas in a liquid is proportional to the pressure of the gas over the solution (Henry’s law). low P low c high P high c

31. Fractional Distillation Apparatus

32. Vapor Pressure Depression Vapor pressure is caused by solvent evaporation Adding a non-volatile solute ALWAYS lowers the vapor pressure – more solute = less solvent at surface = ↓ evaporation = ↓ vapor = ↓ vapor pressure Amount of solute is the only thing that alters this property – colligative property – 1 mol glucose  1 mol glucose – 1 mol NaCl  1 mol Na + and 1 mol Cl - – van’t hoff factor – mol of particles per mol of solute

33. KCl(aq) = K + (aq) + Cl - (aq) CuSO 4 (aq) = Cu +2 (aq) + SO 4 2- (aq) K 2 SO 4 (aq) = 2 K + (aq) + SO 4 2- (aq) K+K+ Cl - K Cl Cu +2 SO 4 2- Cu SO 4 K+K+ SO 4 2- K+K+ KK SO 4

34. Boiling Point Elevation For something to boil the vapor pressure = atmospheric pressure. Adding solute = ↓ vapor pressure = ↑ boiling point Example – adding salt to water before cooking spaghetti noodles causes that water to boil at a hotter temperature, which leads to the noodles cooking faster

35. Freezing Point Depression During freezing, the particles of a solid take on an orderly pattern. Adding solute disrupts this pattern, so even more energy must be removed for the solution to solidify. Examples – applying salt to icy roads helps prevent the water from freezing and the use of antifreeze in vehicles.

36. BPE and FPD Calculations BPE/FPD = kmi k = a different constant for each solvent = positive for BP (.512 kg 0 C/mol for H 2 O) = negative for FP (-1.86 kg 0 C/mol) m = molality i = van’t hoff factor

37. Examples – Colligative Calculations What is the boiling point of a solution that contains 1.25 mol of CaCl 2 in 1400. mL of H 2 O? What is the freezing point of 72.3 g of magnesium sulfate in 1350 mL of H 2 O The freezing point for H 2 O is lowered to -0.390 0 C when 3.90 g of a non-volatile molecular solid is dissolved in 475 g H 2 O. Calculate the molar mass of the substance.

41. Boiling-Point Elevation

42. Osmosis Passive Transport is the selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one. A Semi-Permeable Membrane _____ allows the passage of solvent molecules but blocks the passage of solvent molecules. __________________________ (  ) is the pressure required to stop osmosis. dilute more concentrated

43. A cell in a/an: _Hypotonic_ Solution Low Solute Conc. Isotonic__ solution _Hypertonic__ Solution High Solute Conc.

44. A _Colloid__ is a dispersion of particles of one substance throughout a dispersing medium of another substance. Colloid versus solution Particles: Solution < Colloid < Suspension collodial suspensions have many subtypes based on their medium’s state. Types of Colloids

45. The Cleansing Action of Soap

46. Each soap molecule has a long hydrocarbon chain, sometimes called its 'tail', with a carboxylate 'head'. In water, the sodium or potassium ions float free, leaving a negatively- charged head. The organic part of a natural soap is a negatively-charged, polar molecule. Its hydrophilic (water-loving) carboxylate group (-CO2) interacts with water molecules via ion-dipole interactions and hydrogen bonding. The hydrophobic (water-fearing) part of a soap molecule, its long, nonpolar hydrocarbon chain, does not interact with water molecules. The hydrocarbon chains are attracted to each other by dispersion forces and cluster together, forming structures called micelles. In these micelles, the carboxylate groups form a negatively-charged spherical surface, with the hydrocarbon chains inside the sphere. Because they are negatively charged, soap micelles repel each other and remain dispersed in water. Grease and oil are nonpolar and insoluble in water. When soap and soiling oils are mixed, the nonpolar hydrocarbon portion of the micelles break up the nonpolar oil molecules. A different type of micelle then forms, with nonpolar soiling molecules in the center. Thus, grease and oil and the 'dirt' attached to them are caught inside the micelle and can be rinsed away.

47. Chem. One Review

48. Review 1) Explain how you would prepare 500. mL of a 0.33 M solution of sodium chloride. 2) Determine the molal concentration of a solution in which 320. grams of glucose C 6 H 12 O 6 are dissolved in 4000 grams of water. 3) If the solubility of Carbon Dioxide in water is.625g/L at 790. Torr and 25.0 degrees Celsius; what would be the solubility at constant temperature and 3.00 atm? 4) If water and ethanol mix in all proportions they are said to be? If however water and oil don’t mix at any proportion they are said to be?

49. Colligative Properties Depend only on the number of solute particles present, not on the identity of the solute particles. Among colligative properties are  Vapor pressure depression  Boiling point elevation  Freezing point depression otic pressure

50. Heterogeneous Aqueous Systems Two types: 1. Suspension - a mixture from which particles settle out -suspension differs from a solution because the particles of a suspension are much larger & do not stay suspended (> 1000 nm) - Ex. – muddy water, gravy 2. Colloid -a mixture containing intermediate-sized particles larger than those in solutions but smaller than those in a suspension (1-1000 nm) - Ex. – glue, paint, smoke, milk, fog

51. Colloid Classification Medium / Phases Dispersed phase GasLiquidSolid Continuous medium Gas NONE (All gases are mutually miscible) miscible Liquid aerosol Examples: fog, mist, hair spraysaerosolfog misthair sprays Solid aerosol Examples: smoke, cloud, air particulatessmoke cloudair particulates Liquid Foam Foam Example: whipped cream, Shaving cream whipped cream Shaving cream Emulsion Emulsion Examples: milk, mayonnaise, hand creammilk mayonnaise hand cream Sol Sol Examples: pigmented ink, blood pigmented ink blood Solid Solid foam Examples: aerogel, styrofoam, pumice aerogel styrofoam pumice Gel Gel Examples: agar, gelatin, jellyagar gelatinjelly Solid sol Example: cranberry glass cranberry glass

52. Comparison of Particle Size Solution – Less than 1 nm Colloid – Between 1 nm and 1000 nm Suspension – Larger than 1000 nm

53. Tyndall Effect The scattering of visible light by colloidal particles is called the Tyndall effect. Good test to distinguish between a solution and a colloid.