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Chapter 12. 12.1 What is a solution? mixture –two or more subs. physically combined –no formula, any proportion –retain properties –easily separated by.

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Presentation on theme: "Chapter 12. 12.1 What is a solution? mixture –two or more subs. physically combined –no formula, any proportion –retain properties –easily separated by."— Presentation transcript:

1 Chapter 12

2 12.1 What is a solution? mixture –two or more subs. physically combined –no formula, any proportion –retain properties –easily separated by physical means solution – homogeneous mixture –solute – subs. being dissolved(sugar) particles are 0.1 to 2 nm in size –solvent – subs. doing the dissolving(water)

3 SolutionSoluteSolvent salt watersalt(s)water(l) radiator fluidantifreeze(l)water(l) pop/colaCO 2 (g)water(l) dental fillingHg (l)Ag, Sn, Cu (s) brassCu (s)Zn (s) filter on gas maskpoisonous gas(g)charcoal(s) airO 2 (g)N 2 (g) ???????? (l)??? (g) ???????? (s)??? (g)

4 suspension – two phase heterogeneous mixture – separates particles are >1000 nm in size clay in water dust in air colloid – two phase heterogeneous mixture –remain mixed(usually due to like charged particles) –emulsion/foam particles are 2 to 1000 nm in size milk – fat and casein dispersed in whey glue water – glue dispersed in water

5 Tyndall effect – scattering of light caused by undissolved particles –gaseous or liquid solutions = dissolved - no Tyndall effect –suspensions or colloids = undissolved – positive for Tyndall effect

6 laser light show link

7 separation techniques for mixtures –filter/decant- colloids and suspensions –evaporation – remove liquids from solids –chromatography – separates solutions by molecular sizechromatography –distillation – separates solutions by boiling fractional distillation – separation by boiling point differencesfractional distillation

8 electrolyte –substance that when dissolved or molten conducts electricity carry e - ‘s ions need to be present ionic compounds dissociate when dissolved NaCl(s)  Na + (aq) + Cl - (aq) acid ionization HCl(l)  H + (aq) + Cl - (aq)

9 –What are the electrolytes in Gatorade? –In Gatorade, the key electrolytes are the minerals sodium, potassium and chloride. When athletes sweat, they lose electrolytes such as sodium, potassium, and chloride that are essential to hydration and muscle function. Unlike water and other beverages that are not scientifically formulated, Gatorade is lab-tested to ensure it helps replenish the electrolytes lost in sweat and stimulates thirst so athletes will ingest an adequate amount of fluid and electrolytes to stay better well-hydrated compared to when using beverages without electrolytes, particularly sodium.¹²³

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12 strong electrolyte –completely ionize/dissociate –lots of ions 10 NaCl(s)  10 Na + (aq)+ 10 Cl - (aq) weak electrolyte –partially ionize/dissociate –few ions 10 HC 2 H 3 O 2 (l)  H + (aq) + C 2 H 3 O 2 - (aq) + 9 HC 2 H 3 O 2 (aq) nonelectrolyte –no ionization/dissociation –no ions –molecules(not acids)

13 12.2 The Solution Process solubility – ability of a subs. to specific T and P conditions –hydrophilic “water loving” dissolve in water vitamin C most ionic compounds polar molecules

14 –hydrophobic “water fearing” insoluble in water soluble in fats or oils –vitamin A –wax –styrofoam general rule of solubility –“like dissolves like” –soaps/detergents dissolve in both polar end of soap – attaches to water nonpolar end of soap – attaches to dirt/oil/fat –miscible – mutually soluble –immiscible – does not dissolve laundry ball

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16 surfactants – substance that concentrates at the interface between two phases –solid-liquid, liquid-liquid, liquid-gas –detergent – synthetic surfactant(not natural) generally made from vegetable oil and sulfuric acid often liquid –soap – natural surfactant generally made from sodium/potassium salts of natural animal fatty acids often solid –emulsifying agent - substance, such as soap or eggs, that allows two immiscible liquids to remain dispersed in one another

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18 Sodium Lauryl Sulfate – SLS – An Industrial Detergent SLS is an Engine Degreaser! And it’s in nearly every cleansing product we use from toothpaste to beauty soap. SLS is generally made from petroleum oil and sulfuric acid, and may still contain traces of both. It makes personal products foamy, and is a strong detergent that strips away the skin’s precious oils in addition to removing dirt. Ironically, the FDA actually uses it as a skin irritant to test the anti-irritation properties of various drugs. Sodium Laureth Sulfate Sodium Laureth Sulfate (SLES) is one of the most common shampoo ingredients. In fact most personal hygiene products contain this specific ingredient. SLES is a washing surfactant, in other words a washing detergent. Imagine it as a car polish that returns the shine by removing the top layer of the paint.

19 dissolving –breaking up of solute into the smallest particles that make up the solute ionic compounds -- NaCl  Na + & Cl - ions molecules -- sugar  C 12 H 22 O 11 molecules –occurs at surface of solute (simulation)simulation –methods to increase dissolving rate of a solid in a liquid powdering/crushing –more surface area stirring/agitating –fresh solvent in contact with solute heating –helps separate solute molecules

20 dissolving mechanisms and NRG changes 1)solute(s)  solute(l) NRG is added to solute for phase change dissociation – separation in to ions/molecules endothermic 2)solvent moves apart to allow solute to enter solvent makes room for solute NRG needed to move solvent apart endothermic 3)solute and solvent attract solvation/hydration decrease entropy – release NRG exothermic

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22 if dissolv. mech. 1 & 2 > 3 –dissolving is endothermic –heating increases dissolving –solution feels cold during dissolving –temp. of solution increases during crystallizing cold pack most solutes

23 if dissolv. mech. 1 & 2 < 3 –dissolving exothermic –heating decreases dissolving cooling increases dissolving –not very common NaOH

24 equilibrium – two opposing processes occurring simultaneously –melting/freezing –dissolving/crystallizing if a solution is at equilibrium –undissolved solute remains in solvent crystals in bottom of container –saturated solution – solvent “holding” maximum amount of solute at those conditions

25 if dissolving is occurring faster than crystallizing(not at equillibrium) –no undissolved solute – all solute dissolves –unsaturated solution – solvent holding less than maximum amount of solute dissolving > crystallizing

26 supersaturated solution –unique phenomena –solvent holds more than maximum amount of specified conditions more solute than saturated solution –not common –very easily disturbed honey liquid hand warmers video, video2, video3videovideo2video3

27 solubility of gases in liquids –different than solids/liquids –T affect solubility of gases solubility increases as T of solvent decreases –less molecular motion –gas particles remain isolated –cold liquids dissolve more gases »cloudy ice –hot liquids dissolve less gases »thermal pollution –P affect solubility Henry’s law –solubility of a gas in a liquid is directly related to the P of that gas above the liquid –fizz keeperfizz keeper

28 12.3 Concentration of Solutions concentration – the ratio of solute to solvent –qualitative dilute concentrate

29 quantitative 1)parts per million(ppm) # of solute particles to solution particles 1 ppm = 1 solute particle to 1,000,000 total particles 1 drop of food coloring in 40 gal H 2 O for aqueous solutions = mg solute/L solution What is the concentration in ppm for a solution that has grams of lead in mL of tap water solution? X ppm = 1000 mg x g Pb x 1000 mL 1 g x mL sol x 1L X ppm = 127 mg/L or ppm

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31 Atmospheric carbon dioxide during the last four ice ages. (http://planetforlife.com/co2history/index.html)

32 2)parts per billion(ppb) –micrograms/L (µg/L) –1 ppb = 1 mL of water in an Olympic swimming pool 7 people in the world at current population Sixteen pesticides have been detected in eight brand-name baby foods, according to a study by the Environmental Working Group and the National Campaign for Pesticide Policy Reform, two public interest groups based in Washington, DC. In their study, the EWG and the NCPPR collected a random sampling of 76 jars of baby food from grocery store shelves in Denver, Philadelphia, and San Francisco. The group chose fruits and vegetables babies most commonly eat during their first year of life. Of these, 53% harbored traces of one pesticide, and 18% had two or more pesticides. Plums contained the highest amounts at 46 parts per billion and peaches contained 29 parts per billion. Pears had the highest number of multiple pesticides overall (five).

33 3)molarity(M) # of particles to volume of solution M = mol solute/L solution –vinegar is composed of 5.00 grams of acetic acid(HC 2 H 3 O 2 ) in mL of solution. What is the M of vinegar? M = 1 mole acetic acid x 5.00 g acetic acid g acetic acid x L solution M = mol/L or M

34 4)molality (m) –# particles solute to mass solvent –moles of solute per kilogram of solvent used in calculating freezing point depressions and boiling point elevations 5)karat (k) –concentration of Au in alloys 24 k gold = pure Au 12 k gold = 50% Au & 50% other metal(s)

35 6)mass % (% m/m) –mass of solute per mass solution –used in industry In a regular Coke there is 39 grams of sugar in 355 grams of pop, what is mass %? % m/m = 39 grams sugar/355 grams pop % m/m = 11% sugar 7)%(m/v) –mass of solute(g) per volume solution(mL) –typically used for unsaturated solutions and medicine –saline solution = 0.90%(m/v)

36 Chapter 13 Colligative Properties

37 13.2 Colligative Properties of Solutions –any prop. that affects the solvents physical prop. because of the number of solute particles –adding solute to solvent changes the prop. of the solvent 1)vapor pressure decreases when solute is added to solvent vapor P = P created when a confined liquid evap. less solvent part. at surface to evap. –less evap. = less P –tap water evap. slower than distilled water –sim labsim lab

38 2)freezing point –decreases when solute is added to solvent –freezing pt.(t f ) – temp. at which the vapor P of the solid = vapor P of liquid –since vapor P of liquid is reduced, t f is reduced –solutions freeze at lower temp. than pure solvents more solute particles = lower freezing points (simulated lab)simulated lab

39 freezing pt. depression calculation Δt f = m x K f x i m = molality(mol solute/kg solvent) K f = freezing pt constant(water = 1.86 o C/m) i = van’t Hoff factor = # particles dissoc./ionized

40 freezing pt depression sample problem –What temp. does 175 grams of water freeze if 22.5 grams of sodium chloride is added? Δt f = m x K f x i Δt f = 1 mol NaCl x 22.5 g NaCl x 1.86 o C x g NaCl x Kg H 2 O x m Δt f = 8.18 o C normal t f = 0 o C - Δt f = 8.18 o C new t f = o C

41 How many grams of calcium chloride are needed to lower the freezing point of grams of water to o C? Δt f = 6.55 o C X m = 6.55 o C____ 1.86 o C/m x 3 X m = 1.17 m X g CaCl 2 = g CaCl 2 x 1.17 mol CaCl 2 x Kg 1 mol CaCl 2 x Kg X g CaCl 2 = 97.4 g CaCl 2

42 3)boiling point –increases when solute is added to solvent boiling point = temp. at which the vapor P of the liquid is equal to atmospheric P t b – H 2 O = 100 o 1 atm solute reduces vapor P of solvent more NRG added to get same vapor P t of liquid will be higher to attain vapor P = atm. P solutions have higher boiling points than pure solvents more solute particles = higher boiling points

43 Δt b = m x K b x i m = molality K b = boiling point constant (H 2 O = o C/m) i = van’t Hoff factor My mom always adds salt to the water when she cooks noodles so the noodles cook faster. She adds about 2.0 grams of salt to 1.0 liter of water. What temp. does her water boil? Δt b = 1 mol NaCl x 2.0 g NaCl x o C x g NaCl x 1.0 Kg x m Δt b = o C

44 normal t b = 100 o C + Δt b = o C new t b = o C

45 How many grams of sugar(C 12 H 22 O 11 ) would need to be added to grams of water to increase the boiling point to o C? Δt b = 5.0 o C X m = 5.0 o C________ o C/m x 1 X m = 9.8 m X g = g x 9.8 mol x Kg 1 mol x 1 Kg X g = 1700 g sugar

46 –osmosis movement of solvent through a semipermeable membrane from lower solute conc. to higher solute conc.

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48 osmotic pressure –applied external pressure that stop osmosis –minimum pressure required to stop osmosis

49 osmolarity –concentration of an osmotic solution –osmolarity(osmol/L or osM) = molarity(M) x i –what is osM of saline(sodium chloride) solution(0.90%(m/v))?

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51 dialysis –the process of osmosis in most plant and animal cells solvent molecule, small solute molecules and ions are allowed to pass thru the cell wall or membrane artificial kidney machine

52 isotonic solutions – solutions that have the same osmotic pressure or same osmolarity –blood cells = osmol to osmol dialysing solution has same osmolarity/osmotic pressure as blood but with out the waste waste material passes thru semipermeable membrane/dialysis tubing IV fluids must have same osmolarity/osmotic pressure as blood

53 hypertonic solution – solution with higher osmolarity or osmotic pressure –cell has lower conc. of solute than surrounding solution osmolarity solution > blood (0.30 osM) –water moves out of cells, cells shrink(crenation) –salting foods kills bacteria cells

54 hypotonic solution – solution with lower osmolarity or osmotic pressure –cell contains greater conc. of solute than surrounding solution osmolarity solution < blood(0.27 osM) –water moves into cell, cells swell(hemolysis)

55 reverse osmosis –process that exerts a pressure on the solvent greater than osmotic pressure of solution –causes solvent to move from solution to solvent side of semipermeable membrane

56 fractional distillation video

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