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MixturesMixturesDay 1: Chapter 14Day 1: Chapter 14

Lake Nyos, CameroonLake Nyos, Cameroon

Courtesy of George Kling, page 556-557Courtesy of George Kling, page 556-557

MixtureMixture2 or more 2 or more substances substances

physicallyphysically combinedcombined..

Two Types:Two Types:HomogeneousHomogeneous

Same throughoutSame throughout

HeterogeneouHeterogeneouss

Different throughoutDifferent throughout

HomogeneouHomogeneous?s?

HeterogeneoHeterogeneous?us?

MixtureMixture

Heterogeneous Heterogeneous MixturesMixtures

Suspension: two or Suspension: two or more substances more substances that do NOT mixthat do NOT mix

InsolubleInsoluble

SuspensionsSuspensionsa mixture appearsa mixture appears

uniform when shaken.uniform when shaken.Particles Settle out Particles Settle out Need to shake or stirNeed to shake or stirEx. orange juice, salad Ex. orange juice, salad dressingdressing

SUSPENSIONSUSPENSION

WHY? “LIKES DISSOLVES WHY? “LIKES DISSOLVES LIKES”LIKES”

Polar AND Nonpolar : NOT MIXPolar AND Nonpolar : NOT MIX

- Two substances only go Two substances only go together if they are alike. If together if they are alike. If they aren’t alike NOT go they aren’t alike NOT go together.together.

- Ex. Wax (nonpolar) and water Ex. Wax (nonpolar) and water (polar)(polar)

PolarityPolarity A molecule is A molecule is polarpolar when electrons are when electrons are

shared shared unequallyunequally. Have a (+) and (-) . Have a (+) and (-) endend

Molecules are Molecules are nonpolarnonpolar when when electrons are shared electrons are shared equallyequally between between atomsatoms

Water is very polarWater is very polar

SolutioSolutionn::HomogeneHomogeneous ous MixturesMixtures homogeneous mixture of 2 or homogeneous mixture of 2 or

more substances uniformly more substances uniformly spread throughout a medium.spread throughout a medium.

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Some DefinitionsSome DefinitionsA solution is a A solution is a

HOMOGENEOUSHOMOGENEOUS 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 is usually regarded as usually regarded as the the SOLVENTSOLVENT and and the others as the others as SOLUTESSOLUTES..

Why Mix Uniformly?Why Mix Uniformly?

““Likes dissolve likes”Likes dissolve likes” D6 C30D6 C30

PolarPolar dissolves in dissolves in polarpolar

oror

NonpolarNonpolar dissolves in dissolves in nonpolarnonpolar

Uses: dry cleaningUses: dry cleaning

Microscopic CompositionMicroscopic Composition

Demo: ethanol/waterDemo: ethanol/water

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ColloidColloid

ColloidColloidMany types: we will look at one Many types: we will look at one

EMULSIONSEMULSIONSDo Do notnot settle out or dissolve settle out or dissolve

HOMOGENEOUS, HOMOGENEOUS,

Opaque, not let light throughOpaque, not let light through

Likes Dissolve LikesLikes Dissolve Likes

How do we get two thing that are How do we get two thing that are NOT alike to go together?NOT alike to go together?

Need Need Emulsifying Agent = Emulsifying Agent = thirdthird ingredientingredient

Emulsifying agent is BOTH polar Emulsifying agent is BOTH polar and nonpolarand nonpolar

3. Emulsion3. Emulsion

a mixture where polar a mixture where polar

substance is forced to mix substance is forced to mix uniformly with a nonpolar uniformly with a nonpolar substancesubstance

Held together by emulsifying agentHeld together by emulsifying agentEx. mayonnaise, glueEx. mayonnaise, glue

EMULSIONEMULSION

EMULSIFING EMULSIFING AGENTAGENT

Disk 10: Chapter 20Disk 10: Chapter 20

SOAPS AND DETERGENTSSOAPS AND DETERGENTS

SolutionsSolutions EmulsionsEmulsions

(Colloid)(Colloid)SuspensioSuspensio

nn

Uniform Uniform

HomogeneousHomogeneousDon’t Settle outDon’t Settle out ““Shake”Shake”

HeterogeneousHeterogeneous

TransparentTransparent

Light throughLight throughScatters LightScatters Light

OpaqueOpaqueTwo or more Two or more

phasesphases

Solute and Solute and solventsolvent

Alike (p/p or Alike (p/p or n/n)n/n)

Emulsifying Emulsifying AgentAgent

Polar and Polar and nonpolarnonpolar

Polar with Polar with nonpolarnonpolar

LETS COMPARE LETS COMPARE mixturesmixtures

Mixture Properties Mixture Properties & Particle Size& Particle Size

Dispersed particles too Dispersed particles too bigbig = = suspensionsuspension

Can filter outCan filter out Dispersed particles Dispersed particles smallsmall = =

solutionsolution

Pass through membranePass through membrane

NoneNone TyndallTyndall

effecteffectTyndallTyndall

effecteffect0.1 -1 nm0.1 -1 nm

Atoms, ionsAtoms, ions

Small culesSmall cules

1-200 nm1-200 nm

LargeLarge

moleculesmolecules

> 200nm > 200nm

Pass throughPass through Pass throughPass through Do NOTDo NOT

Pass throughPass through

ThroughThrough

membrane membrane Do NOTDo NOT

Pass through Pass through Do NOTDo NOT

Pass throughPass through

LIGHTSCATTERING

PARTICLESIZE

FILTRATION

DIALYSIS

PropertyProperty SolutionsSolutionsEmulsionsEmulsions

(Colloid)(Colloid) SuspensionSuspension