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1、1SolutionsWhy does a raw egg swell or shrink when Why does a raw egg swell or shrink when placed in different solutions?placed in different solutions?Chemistry I Chapters 15 & 16Chemistry I HD Chapter 15ICP Chapter 22SAVE PAPER AND INK! When you print out the notes on PowerPoint, print Handouts inst
2、ead of Slides in the print setup. Also, turn off the backgrounds (ToolsOptionsPrintUNcheck Background Printing)!2Some DefinitionsA solution is a A solution is a _ mixture of 2 or more mixture of 2 or more substances in a substances in a single phase. single phase. One constituent is One constituent
3、is usually regarded as usually regarded as the the SOLVENT and and the others as the others as SOLUTES. .3Parts of a SolutionSOLUTE the part of a solution that is being dissolved (usually the lesser amount)SOLVENT the part of a solution that dissolves the solute (usually the greater amount)Solute +
4、Solvent = SolutionSoluteSolventExamplesolidsolidsolidliquidgassolidliquidliquidgasliquidgasgas4DefinitionsSolutions can be classified as Solutions can be classified as saturatedsaturated or or ununsaturatedsaturated. .A A saturatedsaturated solution contains solution contains the maximum quantity of
5、 the maximum quantity of solute that dissolves at that solute that dissolves at that temperature.temperature.An An unsaturatedunsaturated solution solution contains less than the contains less than the maximum amount of solute maximum amount of solute that can dissolve at a that can dissolve at a pa
6、rticular temperatureparticular temperature5Example: Saturated and Unsaturated FatsUnsaturated fats have at least one double bond between carbon atoms; monounsaturated means there is one double bond, polysaturated means there are more than one double bond. Thus, there are some bonds that can be broke
7、n, chemically changed, and used for a variety of purposes. These are REQUIRED to carry out many functions in the body. Fish oils (fats) are usually unsaturated. Game animals (chicken, deer) are usually less saturated, but not as much as fish. Olive and canola oil are monounsaturated.Saturated fats a
8、re called saturated because all of the bonds between the carbon atoms in a fat are single bonds. Thus, all the bonds on the carbon are occupied or “saturated” with hydrogen. These are stable and hard to decompose. The body can only use these for energy, and so the excess is stored. Thus, these shoul
9、d be avoided in diets. These are usually obtained from sheep and cattle fats. Butter and coconut oil are mostly saturated fats.6DefinitionsSUPERSATURATED SOLUTIONSSUPERSATURATED SOLUTIONS contain more solute than is contain more solute than is possible to be dissolvedpossible to be dissolvedSupersat
10、urated solutions are Supersaturated solutions are unstable. The supersaturation is unstable. The supersaturation is only temporary, and usually only temporary, and usually accomplished in one of two ways:accomplished in one of two ways:1.1.Warm the solvent so that it will Warm the solvent so that it
11、 will dissolve more, then cool the dissolve more, then cool the solution solution 2.Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.7 SupersaturatedSodium AcetateOne application One application of a of a supersaturated supersaturated solution is
12、the solution is the sodium acetate sodium acetate “heat pack.”“heat pack.”8IONIC COMPOUNDSCompounds in Aqueous SolutionMany reactions involve ionic Many reactions involve ionic compounds, especially reactions in compounds, especially reactions in water water aqueous solutions.aqueous solutions.KMnOK
13、MnO4 4 in water in waterK K+ +(aq) + MnO(aq) + MnO4 4- -(aq)(aq)9How do we know ions are How do we know ions are present in aqueous present in aqueous solutions?solutions?The solutions The solutions _They are called They are called ELECTROLYTESHCl, MgClHCl, MgCl2 2, and NaCl are , and NaCl are stron
14、g electrolytes. They dissociate They dissociate completely (or nearly so) completely (or nearly so) into ions.into ions.Aqueous Solutions10Aqueous SolutionsSome compounds Some compounds dissolve in water but dissolve in water but do not conduct do not conduct electricity. They are electricity. They
15、are called called nonelectrolytes.nonelectrolytes.Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol11Its Time to Play Everyones Favorite Game Show Electrolyte or Nonelectrolyte!12Electrolytes in the BodyCarry messages to Carry messages to and from the brain and
16、 from the brain as electrical signalsas electrical signalsMaintain cellular Maintain cellular function with the function with the correct correct concentrations concentrations electrolyteselectrolytesMake your ownMake your own50-70 g sugar50-70 g sugarOne liter of warm waterOne liter of warm waterPi
17、nch of saltPinch of salt200ml of sugar free fruit 200ml of sugar free fruit squashsquashMix, cool and drinkMix, cool and drink13Concentration of SoluteThe amount of solute in a solution is given by its concentration.Molarity(M)=moles soluteliters of solution141.0 L of 1.0 L of water was water was us
18、ed to used to make 1.0 L make 1.0 L of solution. of solution. Notice the Notice the water left water left over.over.15PROBLEM: Dissolve 5.00 g of NiClPROBLEM: Dissolve 5.00 g of NiCl2 26 6 HH2 2O in enough water to make 250 mL O in enough water to make 250 mL of solution. Calculate the Molarity.of s
19、olution. Calculate the Molarity.Step 1: Step 1: Calculate moles Calculate moles of NiClof NiCl2 26H6H2 2OOStep 2: Step 2: Calculate MolarityCalculate MolarityNiClNiCl2 26 H6 H2 2OO = 0.0841 M16Step 1: Step 1: Change mL to L.Change mL to L.250 mL * 1L/1000mL = 0.250 L250 mL * 1L/1000mL = 0.250 LStep
20、2: Step 2: Calculate.Calculate.Moles = (0.0500 mol/L) (0.250 L) = 0.0125 molesMoles = (0.0500 mol/L) (0.250 L) = 0.0125 molesStep 3: Step 3: Convert moles to grams.Convert moles to grams.(0.0125 mol)(90.00 g/mol) = (0.0125 mol)(90.00 g/mol) = 1.13 gUSING MOLARITYmoles = MVWhat mass of oxalic acid, W
21、hat mass of oxalic acid, H2C2O4, is, isrequired to make 250. mL of a 0.0500 Mrequired to make 250. mL of a 0.0500 Msolution?solution?17Learning CheckHow many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution?1) 12 g2) 48 g3) 300 g18An An IDEAL SOLUTION is is one where the properti
22、es one where the properties depend only on the depend only on the concentration of solute.concentration of solute.Need conc. units to tell us the Need conc. units to tell us the number of solute particles number of solute particles per solvent particle.per solvent particle.The unit “molarity” does n
23、ot The unit “molarity” does not do this!do this!Concentration Units19Two Other Concentration Unitsgrams solutegrams solutegrams solutiongrams solutionMOLALITY, m% by mass% by mass = =% by mass% by mass m of solution = mol solutekilograms solvent20Calculating ConcentrationsDissolve 62.1 g (1.00 mol)
24、of ethylene glycol Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of Hin 250. g of H2 2O. Calculate molality and % by O. Calculate molality and % by mass of ethylene glycol.mass of ethylene glycol. 21Calculating ConcentrationsCalculate molalityCalculate molalityCalculate molality Dissolve 6
25、2.1 g (1.00 mol) of ethylene glycol in 250. g Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of Hof H2 2O. Calculate m & % of ethylene glycol (by mass).O. Calculate m & % of ethylene glycol (by mass).Calculate weight %Calculate weight %22Learning CheckA solution contains 15 g Na2CO3 and 235
26、 g of H2O? What is the mass % of the solution? 1) 15% Na2CO32) 6.4% Na2CO33) 6.0% Na2CO323Using mass %How many grams of NaCl are needed to prepare 250 g of a 10.0% (by mass) NaCl solution? 24Try this molality problem25.0 g of NaCl is dissolved in 5000. mL of water. Find the molality (m) of the resul
27、ting solution.m = mol solute / kg solvent25 g NaCl 1 mol NaCl 58.5 g NaCl= 0.427 mol NaClSince the density of water is 1 g/mL, 5000 mL = 5000 g, which is 5 kg0.427 mol NaCl 5 kg water= 0.0854 m salt water25Colligative PropertiesOn adding a solute to a solvent, the properties On adding a solute to a
28、solvent, the properties of the solvent are modified.of the solvent are modified.Vapor pressure Vapor pressure decreasesdecreasesMelting point Melting point decreasesdecreasesBoiling point Boiling point increasesincreasesOsmosis is possible (osmotic pressure)Osmosis is possible (osmotic pressure)Thes
29、e changes are called These changes are called COLLIGATIVE COLLIGATIVE PROPERTIESPROPERTIES. . They depend only on the They depend only on the NUMBERNUMBER of solute of solute particles relative to solvent particles, not on particles relative to solvent particles, not on the the KINDKIND of solute pa
30、rticles. of solute particles.26Change in Freezing Point The freezing point of a solution is The freezing point of a solution is LOWER than that of the pure solventthan that of the pure solventPure waterPure waterEthylene glycol/water Ethylene glycol/water solutionsolution27Change in Freezing Point C
31、ommon Applications Common Applications of Freezing Point of Freezing Point DepressionDepressionPropylene glycolEthylene glycol deadly to small animals28Common Applications Common Applications of Freezing Point of Freezing Point DepressionDepressionWhich would you use for the streets of Bloomington t
32、o lower the freezing point of ice and why? Would the temperature make any difference in your decision?a)sand, SiO2b)Rock salt, NaClc)Ice Melt, CaCl2Change in Freezing Point 29Change in Boiling Point Common Applications Common Applications of Boiling Point of Boiling Point ElevationElevation30Boiling
33、 Point Elevation and Freezing Point Depression T = Kmii = vant Hoff factor = number of particles i = vant Hoff factor = number of particles produced per molecule/formula unit. For produced per molecule/formula unit. For covalent compounds, i = 1. For ionic covalent compounds, i = 1. For ionic compou
34、nds, i = the number of ions compounds, i = the number of ions present (both + and -)present (both + and -)CompoundCompoundTheoretical Value of iTheoretical Value of iglycolglycol1 1NaClNaCl2 2CaClCaCl2 23 3CaCa3 3(PO(PO4 4) )2 25 531Boiling Point Elevation and Freezing Point Depression T = KmiSubsta
35、nce Kb benzene 2.53 camphor 5.95 carbon tetrachloride 5.03 ethyl ether 2.02 water 0.52 m = molalitym = molalityK = molal freezing K = molal freezing point/boiling point constant point/boiling point constantSubstance Kf benzene 5.12 camphor 40. carbon tetrachloride 30. ethyl ether 1.79 water 1.86 32C
36、hange in Boiling Point Dissolve 62.1 g of glycol (1.00 mol) in 250. g Dissolve 62.1 g of glycol (1.00 mol) in 250. g of water. What is the boiling point of the of water. What is the boiling point of the solution?solution?K Kb b = 0.52 = 0.52 o oC/molal for water (see KC/molal for water (see Kb b tab
37、le). table).SolutionSolutionTTBPBP = K = Kb b m i m i1.1.Calculate solution molality = 4.00 mCalculate solution molality = 4.00 m2.2.TTBPBP = K = Kb b m i m i TTBPBP = 0.52 = 0.52 o oC/molal (4.00 molal) (1)C/molal (4.00 molal) (1) TTBPBP = 2.08 = 2.08 o oC C BP = 100 + 2.08 = 102.08 BP = 100 + 2.08
38、 = 102.08 o oC C (water normally boils at 100)(water normally boils at 100)33Calculate the Freezing Point of a 4.00 molal Calculate the Freezing Point of a 4.00 molal glycol/water solution.glycol/water solution.K Kf f = 1.86 = 1.86 o oC/molal (See KC/molal (See Kf f table) table)SolutionSolutionTTFP
39、FP = K = Kf f m i m i = (1.86 = (1.86 o oC/molal)(4.00 m)(1)C/molal)(4.00 m)(1)TFP = 7.44 FP = 0 7.44 = -7.44 oC(because water normally freezes at 0)Freezing Point Depression34At what temperature will a 5.4 molal solution At what temperature will a 5.4 molal solution of NaCl freeze?of NaCl freeze?So
40、lutionSolutionTTFPFP = K = Kf f m i m i T TFPFP = (1.86 = (1.86 o oC/molal) 5.4 m 2C/molal) 5.4 m 2 T TFP FP = 20.1= 20.1 o oC C FP = 0 20.1 = -20.1 FP = 0 20.1 = -20.1 o oC CFreezing Point Depression35Preparing Solutions Weigh out a solid solute Weigh out a solid solute and dissolve in a given and
41、dissolve in a given quantity of solvent.quantity of solvent. Dilute a concentrated Dilute a concentrated solution to give one solution to give one that is less that is less concentrated.concentrated.36ACID-BASE REACTIONSTitrationsH H2 2C C2 2OO4 4(aq) + 2 NaOH(aq) -(aq) + 2 NaOH(aq) - acidacid baseb
42、aseNaNa2 2C C2 2OO4 4(aq) + 2 H(aq) + 2 H2 2O(liq)O(liq)Carry out this reaction using a Carry out this reaction using a TITRATIONTITRATION. . Oxalic acid,Oxalic acid,H H2 2C C2 2OO4 437Setup for titrating an acid with a base38TitrationTitration1. Add solution from the buret.1. Add solution from the
43、buret.2. Reagent (base) reacts with 2. Reagent (base) reacts with compound (acid) in solution compound (acid) in solution in the flask.in the flask.3.3.Indicator shows when exact Indicator shows when exact stoichiometricstoichiometric reaction has reaction has occurred. (Acid = Base)occurred. (Acid = Base) This is called This is called NEUTRALIZATION.NEUTRALIZATION.
