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SolutionsSolutionsSolutionSolution: Homogeneous mixture, a mixture in which the : Homogeneous mixture, a mixture in which the

components are uniformly intermingled.components are uniformly intermingled.

SolventSolvent: Substance present in the largest amount.: Substance present in the largest amount.

SoluteSolute: Substance present in the smallest amount.: Substance present in the smallest amount.

Aqueous SolutionsAqueous Solutions: Solutions with water as the solvent.: Solutions with water as the solvent.

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SolubilitySolubilityWhat happens when you dissolve NaCl in water?What happens when you dissolve NaCl in water?

When an ionic substance dissolves in water, it breaks up into When an ionic substance dissolves in water, it breaks up into individual cations and anions where are dispersed in water. individual cations and anions where are dispersed in water. There are strong water ions interactions when the solid There are strong water ions interactions when the solid dissolves.dissolves.

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SolubilitySolubility Water also dissolves many nonionic substances. Sugar and Water also dissolves many nonionic substances. Sugar and

ethanol dissolves in water. Both contain polar O-H groups. ethanol dissolves in water. Both contain polar O-H groups. These H-Bond to water molecules. These H-Bond to water molecules.

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SolubilitySolubility Oil and water do not mix. Oil is nonpolar and water is polar. Oil and water do not mix. Oil is nonpolar and water is polar.

Oil floats on the surface of water because its density is less Oil floats on the surface of water because its density is less than that of water.than that of water.

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Solution Composition:Solution Composition:An IntroductionAn Introduction

Saturated SolutionSaturated Solution: A solution that contains as much solute as : A solution that contains as much solute as will dissolve at a given temperature.will dissolve at a given temperature.

Unsaturated SolutionUnsaturated Solution: A solution that has not reached the limit : A solution that has not reached the limit of solute that will dissolve.of solute that will dissolve.

Concentrated SolutionConcentrated Solution: A solution that has a relatively large : A solution that has a relatively large amount of solute dissolved.amount of solute dissolved.

Dilute SolutionDilute Solution: A solution that has a relatively small amount of : A solution that has a relatively small amount of solute dissolved.solute dissolved.

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Making supersaturated Making supersaturated solnssolns

Make sat. solnMake sat. soln Cool it slowly and carefullyCool it slowly and carefully Lower temperatures reduced Lower temperatures reduced

the rate of crystallizationthe rate of crystallization Once disturbed (energy in), Once disturbed (energy in),

causes crystallization to occur causes crystallization to occur excess crystallized out of excess crystallized out of solnsoln

ExothermicExothermic Heat packs of sodium acetate Heat packs of sodium acetate

(can reach 50(can reach 50°C!)°C!) http://www.npr.org/programs/http://www.npr.org/programs/

wesun/features/2001/dec/heatwesun/features/2001/dec/heatpack/011229.heatpack.htmlpack/011229.heatpack.html

Let’s talk about enthalpy of Let’s talk about enthalpy of crystallization in lab #2crystallization in lab #2

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Drinks carbonated under high Drinks carbonated under high pressurepressure

Above 90 atmospheresAbove 90 atmospheres So under COSo under CO22 atmosphere atmosphere Once bottle opened, partial pressure Once bottle opened, partial pressure

of gas above soda plummetsof gas above soda plummets COCO22 solubility decreases drastically solubility decreases drastically Gas bubbles out of solutionGas bubbles out of solution

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The bendsThe bends

Deeper diving has higher pressuresDeeper diving has higher pressures Must use breathing tankMust use breathing tank If it contains NIf it contains N22 then higher pressure then higher pressure

forces Nforces N22 to dissolve in higher amounts in to dissolve in higher amounts in bloodblood

If ascension too fast, lower pressure If ascension too fast, lower pressure causes Ncauses N22 to start bubbling out of blood to start bubbling out of blood too quickly too quickly rupturing of arteries rupturing of arteries excruciatingly painful deathexcruciatingly painful death

Must be rushed to hyperbaric chamberMust be rushed to hyperbaric chamber

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Antifreeze Antifreeze Lowers freezing pt Lowers freezing pt Increases boiling ptIncreases boiling pt Reduces risk of Reduces risk of

radiator “boiling radiator “boiling over”over”

Appreciated during Appreciated during the summer months the summer months in the desertin the desert

Propylene glycol Propylene glycol replacing ethylene replacing ethylene glycolglycol

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Colloids Colloids

From Greek = “glue”From Greek = “glue” Btwn suspensions (fine sand in water, Btwn suspensions (fine sand in water,

mixed up) & solnsmixed up) & solns 1) Have very high molar masses1) Have very high molar masses 2) Have large sizes; starch, for ex.2) Have large sizes; starch, for ex. 3) Tyndall effect 3) Tyndall effect scatter a beam of light scatter a beam of light 4) Do not settle out like suspensions 4) Do not settle out like suspensions 5) Not the same as hemorrhoids5) Not the same as hemorrhoids

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Emulsions Emulsions Colloidal dispersions of one liquid in anotherColloidal dispersions of one liquid in another Mayo, milkMayo, milk Liquids of different polarities are immiscibleLiquids of different polarities are immiscible Need Need emulsifying agentemulsifying agent Such as soap (one polar end, one non) & Such as soap (one polar end, one non) &

proteins (“)proteins (“) In food items In food items soy lecithin soy lecithin In the world of cleaning In the world of cleaning surfacantssurfacants

(soaps, etc.)(soaps, etc.)

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Surfacants Surfacants

NaOH + animal or veggie fat NaOH + animal or veggie fat Na Na++ fatty acidfatty acid--

The fatty acid has a long non-polar The fatty acid has a long non-polar tail and a very polar carboxylate tail and a very polar carboxylate groupgroup

Can be used to take away (clean) Can be used to take away (clean) non-polar entities like oil, dirtnon-polar entities like oil, dirt

Surfacants (soap) used in cleaning = Surfacants (soap) used in cleaning = detergentdetergent

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Detergents Detergents

Lowers surface tension of water (disrupts Lowers surface tension of water (disrupts H-bonding)H-bonding)

Enhances action of detergentEnhances action of detergent Let’s watch the following video:Let’s watch the following video: http://www.ilpi.com/genchem/demo/tensiohttp://www.ilpi.com/genchem/demo/tensio

n/#demon/#demo

Sodium lauryl sulfate (soaps, shampoos)Sodium lauryl sulfate (soaps, shampoos)

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Solution Composition:Solution Composition:Mass PercentMass Percent

Mass PercentMass Percent: or weight percent; describes a solution’s : or weight percent; describes a solution’s composition.composition.

The equation for Mass Percent is given below.The equation for Mass Percent is given below.

Mass Percent =Mass Percent = mass of solute mass of solute x 100%x 100%

mass of mass of solutionsolution

Mass Percent =Mass Percent = grams of solute grams of solute x 100%x 100%

grams of solute + grams of solventgrams of solute + grams of solvent

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Solution Composition:Solution Composition:Mass PercentMass Percent

ExampleExample

A 135 g sample is evaporated to dryness, leaving 4.73 g of solid A 135 g sample is evaporated to dryness, leaving 4.73 g of solid residue. Calculate the mass percent of solute present.residue. Calculate the mass percent of solute present.

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Solution Composition: Solution Composition: MolarityMolarity

MolarityMolarity: Number of moles of solute per volume of solution in : Number of moles of solute per volume of solution in liters.liters.

Example: A solution that is 1.0 M contains 1.0 mol per 1 L of Example: A solution that is 1.0 M contains 1.0 mol per 1 L of solution.solution.

The equation for Molarity is given below.The equation for Molarity is given below.

M = Molarity =M = Molarity = moles of solute moles of solute == mol mol

liters of solution Lliters of solution L

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Solution Composition: Solution Composition: MolarityMolarity

Standard SolutionStandard Solution: Solution whose concentration is accurately : Solution whose concentration is accurately known.known.

Stock SolutionStock Solution: Solutions that are routinely used and purchased : Solutions that are routinely used and purchased or prepared in concentrated form.or prepared in concentrated form.

DilutionDilution: The process of adding more solvent to a solution. Only : The process of adding more solvent to a solution. Only water is added in a dilution.water is added in a dilution.