1. Solutions

2. Classification of Matter Solutions Solutions are homogeneous mixtures

3. Properties of Solutions, Suspensions, and Colloids

4. There are two types: 1. Suspensions 2. Colloids *Suspensions and colloids are not solutions. Heterogeneous Liquid Mixtures

5. Suspensions Colloids Solutions

6. ColloidsSuspensions HomogeneousHeterogeneous Particle size: 0.01-1 nm; can be atoms, ions, molecules Particle size: 1-1000 nm, dispersed; can be large molecules Particle size: Over 1000 nm, suspended; can be large particles Do not separate on standing Particles settle out Cannot be separated by filtration Most cannot be separated by filtration All can be separated by filtration Do not scatter light Scatter light (Tyndall effect) Not transparent May scatter lite

7. The Tyndall Effect Many colloids appear homogeneous because the individual particles cannot be seen. The particles are, however, large enough to scatter light. Tyndall effect is a property that can be used to distinguish between a solution and a colloid.

8. When a laser is passed through a solution and a colloid at the same time, it is evident which glass contains the colloid. (you can’t see the light in a colloid) Colloid Solution

9. Solutions Solutions: a homogeneous mixture of two or more substances in a single phase of matter. In a simple solution where, for example, salt is dissolved in water, the particles of one substance are randomly mixed with the particles of another substance.

10. SOLUTE – A solute is the dissolved substance in a solution. Present in lesser amount. EX: CO 2, KCl, Na 2 CO 3 SOLVENT – A solvent is the dissolving medium in a solution. Present in greater amount. EX: H 2 O, CCl 4

11. Solution Concentration

12. Molarity is simply a measure of the "strength" of a solution. A solution that we would call "strong" would have a higher molarity than one that we would call "weak". If you ever made or drank a liquid made from a powdered mix, such as Kool-Aid or hot cocoa, you probably are familiar with the difference between what is called a "weak" solution or a "strong" solution.

13. To make Kool-Aid of "normal“ strength = 4 scoops of powder ----------------------- 2 quarts of water To make Kool-Aid twice the "normal" strength… What could you do? 8 scoops of powder 4 scoops of powder -------------------- or -------------------- 2 quarts of water 1 quart water

14. Solution Concentration Molarity: *Molarity (M) = moles solute Liter(s) solution One mole of NaCl (molar mass of NaCl = 22.99 + 35.45 = 58.44 grams) is dissolved in enough water (1 Liter) to make a 1M NaCl solution.

15. Colligative Properties Colligative comes from the Greek word kolligativ meaning glue together. We use this term for the properties of substances (solutes and solvents) together. Colligative properties of solutions is used to describe the effects of antifreeze/summer coolant.

16. The addition of a nonvolatile solute will require a higher temperature in which to reach boiling point, thus: Boiling point elevation The addition of a nonvolatile solute will require a lower temperature in which to reach freezing point, thus Freezing point depression

17. Pure water Water with NaCl The water with the solute of NaCl has fewer liquid molecules becoming gases. This will increase the temp needed to change the state from (l)  (g)

18. Calculating Freezing and Boiling Points The following table contains the molal (K) Boiling Point Elevations, K b, and Freezing Point Depressions, K f. SolventNormal boiling pt (°C) K b (°C/m) Normal freezing pt (°C) K f (°C/m) Water100.00.520.01.86 Benzene80.12.535.55.12 Ethanol78.41.22-114.61.99 CCl 4 76.85.02-22.329.8 Chloroform61.23.63-63.54.68

19. Coolant is used because it takes higher temperatures to reach boiling point. Antifreeze needs lower temperatures in order to freeze. This also why salt is used on frozen roads and walkways. The salt dissolves in the water and lowers the freezing point of water. It now takes colder temps to turn the water into ice. A 10-percent salt solution freezes at 20 F (-6 C), and a 20-percent solution freezes at 2 F (-16 C).

20. Acids, Bases and Salts

21. Theories of Acid/Base Acids – produce H + Bases - produce OH - Acids – donate proton (H + ) Bases – accept protons (H + ) Acids – accept e - pair Bases – donate e - pair 1. Arrehenius 2. Bronsted-Lowry 3. Lewis only in water any solvent used in organic chemistry. wider range of substances

22. Properties of Acids Acid Property #1. The word acid comes from the Latin word acere. which means "sour“. All acids taste sour. Acid Property #2. In 1663. Robert Boyle wrote that acids would make a blue vegetable dye called "litmus" turn red. Acid Property #3. Acids destroy the chemical properties of bases.

23. Properties of Acids Cont. Acid Property #4. Acids conduct an electric current. (electrolytes) Acid Property #5. Upon chemically reacting with an active metal. acids will evolve hydrogen gas (H 2 ).

24. #6. Acids Have a pH less than 7

25. Properties of Bases Base Property #1. The word "base" has a more complex history and its name is not related to taste. All bases taste bitter. Base Property #2. Bases are substances which will restore the original blue color of litmus after having been reddened by an acid. Base Property #3. Bases destroy the chemical properties of acids.

26. Properties of Bases Cont. Base Property #4. Bases conduct an electric current. (electrolytes) Base Property #5. Bases feel slippery. sometimes people say soapy. This is because they dissolve the fatty acids and oils from your skin and this cuts down on the friction between your fingers as you rub them together.

27. #6. Bases have a pH greater than 7 VIDEO

28. Properties of A Salt A salt is the combination of a cation(+ metal ion) and an anion (- nonmetal ion). Salts are products of the reaction between acids and bases. Solid salts usually make crystals. If a salt dissolves in water solution. it usually dissociates into the anions and cations that make up the salt.

29. Strong Acids and Bases Strong acids are those that ionize completely in water. The dissociation of a strong acid looks like the diagram at the right in that it dissociates completely into positive and negative ions.

30. HA Let’s examine the behavior of an acid. HA. in aqueous solution. What happens to the HA molecules in solution?

31. HA H+H+ A-A- Strong Acid 100% dissociation of HA Would the solution conduct electricity?

32. Weak Acids and Bases Some acids and bases ionize only slightly in water. These are considered weak. The most important weak base is ammonia (NH 3 ).

33. HA H+H+ A-A- Weak Acid Partial dissociation of HA Would the solution conduct electricity?

34. HA H+H+ A-A- Weak Acid HA  H + + A - At any one time. only a fraction of the molecules are dissociated.

35. Strong Acids *HNO 3 - nitric acid *HCl - hydrochloric acid *H 2 SO 4 - sulfuric acid *HClO 4 - perchloric acid *HBr - hydrobromic acid *HI - hydroiodic acid *HClO 3 - chloric acid *Refer to solubility rules.

36. Strong Bases *LiOH - lithium hydroxide *NaOH - sodium hydroxide *KOH - potassium hydroxide *RbOH - rubidium hydroxide *CsOH - cesium hydroxide *Ca(OH) 2 - calcium hydroxide *Sr(OH) 2 - strontium hydroxide *Ba(OH) 2 - barium hydroxide *Refer to solubility rules for soluble hydroxides

37. Neutralization Reactions The word "neutralization" is used to describe the double replacement reaction of an acid plus a base because the acid and base properties of H + and OH - are destroyed or neutralized. In the reaction. H + and OH - combine to form water and a salt.

38. Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide. Mg(OH) 2. which neutralizes stomach acid. HCl. 2 HCl + Mg(OH) 2 MgCl 2 + 2 H 2 O

39. In general: Acid + Base  Water + Salt HCl + NaOH  NaCl + HOH H 2 O HCl + Mg(OH) 2  H 2 O + ______ H 2 SO 4 + NaOH  H 2 O + ______ Bases Neutralize Acids MgCl 2 Na 2 SO 4

40. When acids and bases are equal in strength and concentration. a neutral (pH = 7) solution is formed. EX: HCl + NaOH --> H 2 O + NaCl (Strong acid) (Strong Base) HF + Mg(OH) 2 --> H 2 O + MgF 2 (Weak acid) (Weak Base)

41. Neutral solutions have an equal number of hydroxide & hydronium ions Acidic Neutral Solution

42. pH and pOH

43. The scale is measured on a log scale of 0 to 14. with each unit representing a ten-fold change.

44. pH Scale The pH scale is a measure of hydrogen ion [H + ] concentration (acid molarity) as well as the hydroxide [OH-] concentration (base molarity). Hydrogen ion concentration indicates: – Acids will have a pH of 0-6 Hydroxide ion concentration indicates: – Bases will have a pH of 8-14 The higher the [H + ]. the higher the acidity. the higher the [OH-]. the higher the basicity.

45. Some common pH values

46. Calculating pH The concentration (M or mol/L) of H + is expressed in powers of 10. from 10 -14 to 10 0. Scientists use the following formula to calculate pH using acid molarity. pH = -log [H + ] (acid Molarity) (Remember that the [ ] mean Molarity)

47. Example pH Calculations pH = -log [H + ] EX: 0.50M HCl is added to water to make a final volume of 1 liter. What is the pH of this solution? Step 1: Identify that you have an acid (starts with an H) Step 2: Identify [H + ] = 0.50 M Step 3: Place value in equation and solve. pH = -log[0.50] = 0.30 pH (Acidic) (pH less than 7)

48. Practice pH Calculations pH = -log [H + ] Find pH of the following solutions if [H + ] is: 1. 1.00 x 10 -3 M = 3.00 pH 2. 6.59 x 10 -6 M = 5.18 pH 3. 9.47 x 10 -10 M = 9.02 pH I-phones & Calculators: -log(6.59ee-6)enter = answer (2 decimal places )

49. pOH Just like pH can be calculated from the [H+] concentration… pH = -log [H + ] pOH can be calculated from the [OH - ] concentration… pOH = -log [OH - ]

50. pOH Just like [H+] concentration can be calculated from pH… [H + ] = alog (-pH) [OH - ] concentration can be calculated from pOH… [OH - ] = alog (-pOH)

51. Connecting pH to pOH You can calculate the pH of a solution if you know the concentration of hydroxide ion. [OH-] If we use the ion product constant of water we can derive this equation: [pH] x [pOH] = 1.00 x 10 -14 Working with this equation leads to: pH + pOH = 14

52. Practice pH Calculations Using pOH EX: Find the pH of a solution with an [OH - ] of 1.0 x 10 -8 M. Step 1: Calculate pOH by using equation: pOH = -log[OH - ] = -log(1.0 x 10 -8 )= 8 pH Step 2: Subtract the pOH from 14 to find pH: pH = 14 - pOH = 14 - 8 = 6 pH

53. Practice pH Calculations Using pOH Find the pH of the following solutions with [OH - ] of: 1. 1.00 x 10 -4 M -log[1.00x10 -4 ] = 4 pOH, 14-4=10 pH 2. 2.64 x 10 -13 M -log[2.64x10 -13 ] = 12 pOH, 14-12=2 pH 3. 5.67 x 10 -2 M -log[5.67x10 -2 ] = 1.25 pOH, 14-1.25=12.75 pH 4. 3.45 x 10 -11 M -log[3.45x10 -11 ] = 10.46 pOH, 14-10.46=3.54 pH

54. Summary of pH and pOH pH = -log[H + ] (acid concentration) pOH = -log[OH - ] (base concentration) pH + pOH = 14 *Hints: 1. Identify initial substance as acid or base to determine if you have H + or OH -. 2. Label all concentrations with M unit.