11

AnnouncementsAnnouncements & Agenda& Agenda (02/16/07)(02/16/07)

Please pick up exams if you haven’t.Please pick up exams if you haven’t.

Mon: Movie in VDW 102– You must attend & Mon: Movie in VDW 102– You must attend & complete a worksheet!complete a worksheet!

TodayToday Solution Concentrations (7.4, 7.5)Solution Concentrations (7.4, 7.5) Solution Properties & Some Other Mixtures (7.7)Solution Properties & Some Other Mixtures (7.7) Osmosis (7.7)Osmosis (7.7)

22

30 Good Practice Problems (Ch 7)30 Good Practice Problems (Ch 7)

11 22 33 44 55

7.01, 7.03, 7.11, 7.13, 7.15, 7.17, 7.01, 7.03, 7.11, 7.13, 7.15, 7.17, 7.25, 7.27, 7.29, 7.31, 7.35, 7.37, 7.25, 7.27, 7.29, 7.31, 7.35, 7.37, 7.41, 7.45, 7.49, 7.53, 7.55, 7.61, 7.41, 7.45, 7.49, 7.53, 7.55, 7.61, 7.63, 7.65, 7.69, 7.71, 7.75, 7.77, 7.63, 7.65, 7.69, 7.71, 7.75, 7.77, 7.83, 7.87, 7.89, 7.93, 7.97, 7.997.83, 7.87, 7.89, 7.93, 7.97, 7.99

33

Last Time: Nature of SolutionsLast Time: Nature of Solutions

SolutionSolution – homogeneous mixture of two or – homogeneous mixture of two or more substancesmore substances SolventSolvent – the main medium, present in the – the main medium, present in the

largest quantitylargest quantity SoluteSolute – material dissolved in the solvent – material dissolved in the solvent

They don’t just have to be liquids:They don’t just have to be liquids:

44

Last Time: “Like Dissolves Like”Last Time: “Like Dissolves Like”

What does this mean?What does this mean?Answer: compatibility of intermolecular Answer: compatibility of intermolecular forces (last week)forces (last week)Typically, compounds with similar polarity Typically, compounds with similar polarity will be soluble in each other.will be soluble in each other.Predicting trends based on properties…Predicting trends based on properties…

55

Which of the following vitamins are fat-soluble Which of the following vitamins are fat-soluble and which are water soluble?and which are water soluble?

Vitamins: organic Vitamins: organic molecules required for molecules required for proper function but not proper function but not made by the body. made by the body. (Obtain by eating!)(Obtain by eating!)

2 categories: 2 categories:

fat-soluble (dissolve in fat-soluble (dissolve in fatty hydrocarbon-like fatty hydrocarbon-like tissues) tissues)

water-solublewater-soluble

Why we need at least some oil & fat in our diet!Why we need at least some oil & fat in our diet!

66

In water, In water, • strong electrolytesstrong electrolytes produce ions and conduct an produce ions and conduct an

electric current. electric current. • weak electrolytesweak electrolytes produce a few ions. produce a few ions. • nonelectrolytesnonelectrolytes do not produce ions. do not produce ions.

Last Time: Solutes & Ionic ChargeLast Time: Solutes & Ionic Charge

77

• the maximum amount of solute that the maximum amount of solute that dissolves in a specific amount of solvent. dissolves in a specific amount of solvent.

• expressed as grams of solute in 100 expressed as grams of solute in 100 grams of solvent water.grams of solvent water.

g of soluteg of solute

100 g water100 g water

Solubility & Concentration (7.3-7.4)Solubility & Concentration (7.3-7.4)

Unsaturated vs. Saturated SolutionsUnsaturated vs. Saturated Solutions

88

At 40At 40C, the solubility of KBr is 80 g/100 g HC, the solubility of KBr is 80 g/100 g H22O.O.

Identify the following solutions as eitherIdentify the following solutions as either1) saturated or 2) unsaturated. Explain.1) saturated or 2) unsaturated. Explain.

A. 60 g KBr added to 100 g of water at 40A. 60 g KBr added to 100 g of water at 40C.C.

B. 200 g KBr added to 200 g of water at 40B. 200 g KBr added to 200 g of water at 40C.C.

C. 25 g KBr added to 50 g of water at 40C. 25 g KBr added to 50 g of water at 40C.C.

Learning CheckLearning Check

What happens to the “leftover” solute???What happens to the “leftover” solute???

99

Effect of Temperature on SolubilityEffect of Temperature on Solubility

• Depends on Temp!Depends on Temp!

• Solids: usually Solids: usually increases as increases as temperature inc.temperature inc.

• Gases: usually Gases: usually decreases as decreases as temperature inc.temperature inc.

1010

Solubility and PressureSolubility and PressureHenry’s Law:Henry’s Law:

• Gas solubility is Gas solubility is directly related to directly related to gas pressure above gas pressure above the liquidthe liquid

• at higher pressures, at higher pressures, more gas molecules more gas molecules dissolve in the dissolve in the liquid.liquid.

Real life examples… soda, the bends, etc.Real life examples… soda, the bends, etc.

1111

The amount of solute dissolved in a specific The amount of solute dissolved in a specific amount of solution.amount of solution.

amount of soluteamount of solute

amount of solutionamount of solution

Comes in all sorts of fantastic flavors!Comes in all sorts of fantastic flavors!• Mass PercentMass Percent• Volume PercentVolume Percent• Mass/Volume PercentMass/Volume Percent• MolarityMolarity

Percent Concentration (7.4)Percent Concentration (7.4)

1212

• concentration is the percent by mass of concentration is the percent by mass of solute in a solution.solute in a solution.

mass percent = mass percent = g of solute g of solute x 100 x 100

g of solute + g of solventg of solute + g of solvent

• amount in g of solute in 100 g of solution.amount in g of solute in 100 g of solution.

mass percent = mass percent = g of solute g of solute x 100x 100

100 g of solution100 g of solution

Mass Percent (% m/m)Mass Percent (% m/m)

1313

Mass of SolutionMass of Solution

8.00 g KCl8.00 g KCl

50.00 g KCl 50.00 g KCl solutionsolution

Add water to Add water to give 50.00 g give 50.00 g solutionsolution

1414

Calculation of mass percent (% m/m) requires theCalculation of mass percent (% m/m) requires the

• grams of solute (g KCl) andgrams of solute (g KCl) and

• grams of solution (g KCl solution).grams of solution (g KCl solution).

g of KCl g of KCl = = 8.00 g 8.00 g

g of solvent (water) g of solvent (water) = = 42.00 g42.00 g

g of KCl solution g of KCl solution = = 50.00 g50.00 g

8.00 g KCl (solute) 8.00 g KCl (solute) x 100 = 16.0% (m/m) x 100 = 16.0% (m/m)

50.00 g KCl solution50.00 g KCl solution

Calculating Mass PercentCalculating Mass Percent

1515

• percent volume (mL) of solute (liquid) to volume percent volume (mL) of solute (liquid) to volume (mL) of solution.(mL) of solution.

volume % (v/v) = volume % (v/v) = mL of solute mL of solute x 100 x 100 mL of solution mL of solution

• solute (mL) in 100 mL of solution.solute (mL) in 100 mL of solution.

volume % (v/v) = volume % (v/v) = mL of solute mL of solute 100 mL of solution 100 mL of solution

Volume Percent (% v/v)Volume Percent (% v/v)

1616

• percent mass (g) of solute to volume (mL) of percent mass (g) of solute to volume (mL) of solution.solution.

mass/volume % (m/v) = mass/volume % (m/v) = g of solute g of solute x x 100100 mL of solution mL of solution

• solute (g) in 100 mL of solution.solute (g) in 100 mL of solution.

mass/volume % (m/v) = mass/volume % (m/v) = g of solute g of solute x x 100 100 100 mL of solution 100 mL of solution

Mass/Volume Percent (% m/v)Mass/Volume Percent (% m/v)

1717

Percent Conversion FactorsPercent Conversion Factors

Two conversion factors can be written for Two conversion factors can be written for each type of % value.each type of % value.

TABLE 7.7

5% (m/v) glucose There are 5 g of glucose 5 g glucose and 100 mL solution

in 100 mL of solution. 100 mL solution 5 g glucose

1818

How many grams of NaOH are needed to How many grams of NaOH are needed to prepare 75.0 g of 14.0% (m/m) NaOH solution?prepare 75.0 g of 14.0% (m/m) NaOH solution?

0%

0%

0% 1) 10.5 g NaOH1) 10.5 g NaOH

2) 75.0 g NaOH2) 75.0 g NaOH

3) 536 g NaOH3) 536 g NaOH

11 22 33 44 55

1919

1)1)10.5 g NaOH10.5 g NaOH

75.0 g solution x 75.0 g solution x 14.0 g NaOH 14.0 g NaOH = 10.5 g = 10.5 g NaOHNaOH

100 g solution100 g solution

14.0% (m/m) factor14.0% (m/m) factor

SolutionSolution

2020

How many milliliters of a 5.75% (v/v) ethanol How many milliliters of a 5.75% (v/v) ethanol solution can be prepared from 2.25 mL ethanol?solution can be prepared from 2.25 mL ethanol?

11 22 33 44 55

0%

0%

0% 1) 2.56 mL1) 2.56 mL

2) 12.9 mL2) 12.9 mL

3) 39.1 mL3) 39.1 mL

2121

3) 39.1 mL 3) 39.1 mL

2.25 mL ethanol x 2.25 mL ethanol x 100 mL solution 100 mL solution 5.75 mL 5.75 mL

ethanolethanol

5.75% (v/v) inverted5.75% (v/v) inverted

= 39.1 mL solution= 39.1 mL solution

SolutionSolution

2222

Molarity and Dilution (7.5)Molarity and Dilution (7.5)

MolarityMolarity (M) is (M) is

• a chemist’s concentration term for solutions.a chemist’s concentration term for solutions.

• gives the moles of solute in 1 L solution.gives the moles of solute in 1 L solution.

• moles of solutemoles of soluteliter of solution liter of solution

2323

Preparing a 1.0 Molar SolutionPreparing a 1.0 Molar SolutionA 1.00 M NaCl solution is preparedA 1.00 M NaCl solution is prepared• by weighing out 58.5 g NaCl (1.00 mole) by weighing out 58.5 g NaCl (1.00 mole)

andand• adding water to make 1.00 liter of solution.adding water to make 1.00 liter of solution.

2424

DDilutionilution

In a In a dilutiondilution

• water is added.water is added.

• volume increases.volume increases.

• concentration decreases.concentration decreases.

2525

Comparing Initial & Diluted SolutionsComparing Initial & Diluted SolutionsIn the initial and diluted solution,In the initial and diluted solution,

• the amount of solute is the same.the amount of solute is the same.

• the concentrations and volumes are related by the the concentrations and volumes are related by the following equations:following equations:

For percent concentration:For percent concentration:

CC11VV11 = C = C22VV22

initial dilutedinitial diluted

For molarity:For molarity:

MM11VV11 = M = M22VV22

initial dilutedinitial diluted

2626

Summary: Properties of SolutionsSummary: Properties of Solutions

• contain small particles (ions or molecules).contain small particles (ions or molecules).

• are transparent.are transparent.

• do not separate*.do not separate*.

• cannot be filtered.cannot be filtered.

• do not scatter light.do not scatter light.

2727

ColloidsColloids

• have medium size particles. have medium size particles.

• cannot be filtered. cannot be filtered.

• can be separated by semipermeable can be separated by semipermeable

membranes.membranes.

• scatter light (Tyndall effect).scatter light (Tyndall effect).

2828

Examples of ColloidsExamples of Colloids

• FogFog

• Whipped creamWhipped cream

• MilkMilk

• CheeseCheese

• Blood plasmaBlood plasma

• PearlsPearls

2929

SuspensionsSuspensions

• have very large particles.have very large particles.

• settle out. settle out.

• can be filtered. can be filtered.

• must be stirred to stay suspended.must be stirred to stay suspended.

Examples include blood platelets, muddy water, Examples include blood platelets, muddy water,

and lotions.and lotions.

3030

OsmosisOsmosis

• water (solvent) flows water (solvent) flows from the lower solute from the lower solute concentration into the concentration into the higher solute higher solute concentration. concentration.

• the level of the solution the level of the solution with the higher with the higher concentration rises.concentration rises.

• the concentrations of the concentrations of the two solutions the two solutions become equal with time.become equal with time.

3131

Suppose a semipermeable membrane separates a 4%Suppose a semipermeable membrane separates a 4%

starch solution from a 10% starch solution. Starch is astarch solution from a 10% starch solution. Starch is a

colloid and cannot pass through the membrane, butcolloid and cannot pass through the membrane, but

water can. What happens?water can. What happens?semi-semi-

permeable permeable membranemembrane

4% starch4% starch

OsmosisOsmosis

10% starch10% starchH2O

3232

7% starch

Water Flow EqualizesWater Flow Equalizes

• The 10% starch solution is diluted by the flow of water out The 10% starch solution is diluted by the flow of water out of the 4% and its volume increases.of the 4% and its volume increases.

• The 4% solution loses water and its volume decreases.The 4% solution loses water and its volume decreases.

• Eventually, the water flow between the two becomes Eventually, the water flow between the two becomes equal.equal.

7% starch

H2O

3333

Osmotic PressureOsmotic Pressure

• produced by the solute particles dissolved in produced by the solute particles dissolved in a solution.a solution.

• equal to the pressure that would prevent the equal to the pressure that would prevent the flow of additional water into the more flow of additional water into the more concentrated solution.concentrated solution.

• greater as the number of dissolved particles greater as the number of dissolved particles in the solution increases.in the solution increases.

3434

Osmotic Pressure of the BloodOsmotic Pressure of the Blood

Red blood cellsRed blood cells

• have cell walls that are semipermeable have cell walls that are semipermeable membranes.membranes.

• maintain an osmotic pressure that cannot maintain an osmotic pressure that cannot change or damage occurs. change or damage occurs.

• must maintain an equal flow of water must maintain an equal flow of water between the red blood cell and its between the red blood cell and its surrounding environment. surrounding environment.

3535

Isotonic SolutionsIsotonic Solutions• exerts the same osmotic exerts the same osmotic

pressure as red blood pressure as red blood cells. cells.

• is known as a is known as a “physiological solution”.“physiological solution”.

• of 5.0% glucose or 0.90% of 5.0% glucose or 0.90% NaCl is used medically NaCl is used medically because each has a solute because each has a solute concentration equal to the concentration equal to the osmotic pressure equal to osmotic pressure equal to red blood cells.red blood cells.

H2O

3636

Hypotonic SolutionsHypotonic Solutions

• has a lower osmotic has a lower osmotic pressure than red blood pressure than red blood cells.cells.

• has a lower has a lower concentration than concentration than physiological solutions. physiological solutions.

• causes water to flow into causes water to flow into red blood cells.red blood cells.

• causes hemolysis: RBCs causes hemolysis: RBCs swell and may burst.swell and may burst.

H2O

3737

Hypertonic SolutionsHypertonic Solutions

• has a higher osmotic has a higher osmotic pressure than RBCs.pressure than RBCs.

• has a higher has a higher concentration than concentration than physiological physiological solutions. solutions.

• causes water to flow causes water to flow out of RBCs.out of RBCs.

• cause crenation: cause crenation: RBCs shrinks in size.RBCs shrinks in size.

H2O

3838

DialysisDialysis

In In dialysisdialysis,,

• solvent and small solute particles pass solvent and small solute particles pass through an artificial membrane.through an artificial membrane.

• large particles are retained inside.large particles are retained inside.

• waste particles such as urea from blood are waste particles such as urea from blood are removed using hemodialysis (artificial removed using hemodialysis (artificial kidney). kidney).