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Mixtures, Mixtures, Solutions, Solutions, and Waterand Water

Unit 7AUnit 7A

2Types of MixturesTypes of MixturesReview: When we classified matter, we learned

that mixtures can be classified as:

Homogeneous (visually the same throughout) or Heterogeneous visually different throughout)

What are some examples of each of these types of mixtures?

3SuspensionSuspension: : a a heterogeneousheterogeneous mixture of mixture of

2 or more substances2 or more substancesParticles areParticles are largelarge enough enough to settle out to settle out and can be and can be separated byseparated by filteringfilteringi.e. – Muddy i.e. – Muddy

waterwater

4Flour suspended in water (appears light blue

because blue light is scattered off the flour particles to a greater extent than red light)

Other examples:

•Chalk Dust suspended in the air

•Paint

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Colloids:Colloids: homogeneoushomogeneous mixture of 2 or more mixture of 2 or more substances substances evenlyevenly blendedblended into one another.into one another.Substances Substances nevernever

separate (settle out)separate (settle out)

7What’s the What’s the differencedifference between a between a solution and solution and

colloidcolloid??

ColloidsColloids havehave largerlarger particlesparticles thatthat scatter light;scatter light; SolutionsSolutions havehave smallersmaller particlesparticles that do that do not scatter the lightnot scatter the light

Use the:

Is fog a Is fog a solution or solution or

colloid?colloid?

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A A solutionsolution is... is...Def. - A homogenous mixture of two

or more substancesThe Formation of a solution is a physical change …NOTNOT a chemical

change.

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Solute:Solute: the substance the substance that is that is being being dissolved dissolved

•Present in the smallest Present in the smallest amountamount

Solvent:Solvent: component component presentpresent in thein the largestlargest

amountamount (usually H(usually H22O).O).

12Types of Liquid Solutions

AqueousAqueousA solution with water

as the solvent

TinctureTinctureA solution with alcohol

as the solvent

13Solution ConcentrationSolution Concentration Refers to the amount of solute

dissolved in a solvent

5 grams5 grams of salt in of salt in 100 grams of 100 grams of waterwaterdilutediluteVSVS

35 grams35 grams of of salt in salt in 100 100 grams of grams of

waterwaterconcentratedconcentrated

100 g.

100 g.

5 g

35 g

14Concentrated vs. DiluteConcentrated vs. Dilute

A concentrated solution contains:

Large amount of SOLUTE in a small amount of SOLVENT

A dilute solution contains:

Small amount of SOLUTE dissolved in a large amount of SOLVENT

“from concentrate”

SUMMARY

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Does a solution always have to a be

liquid?

NO!!NO!!

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Solid into a Solid (alloy):Solid into a Solid (alloy): two metals dissolved into two metals dissolved into one another. one another.

Solid into a Liquid:Solid into a Liquid: Salt Salt dissolved in water.dissolved in water.

Gas into a Liquid:Gas into a Liquid: COCO22 dissolved (under pressure) dissolved (under pressure) into a coke. into a coke.

18The air that we The air that we

breathe is also a breathe is also a solution because it solution because it is made up of many is made up of many

different gases.different gases.

78.09% Nitrogen

20.95% Oxygen

Argon, CO2, and other trace gasesThe “solvent”

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Day 2 – Day 2 – Solubility Solubility GraphsGraphs

20DissolvingDissolving Def: the process of creating a solution

through the mixing of solute and solvent particles

Can a solute be dissolved by any solvent? NO!! NO!!

21InsolubleInsoluble When a substance cannot be dissolved in a solvent...

OilOil waterwater

++ ==

The word solublesoluble refers to solutes that CAN be dissolved in a

particular solvent.

22The Exxon Valdez Oil Spill of 1989

23SolubilitySolubilityA measure of how much solute

can be dissolved in a solvent under certain conditions (i.e. – temp. & pressure)

Example

24Limits of SolubilityLimits of Solubility

SupersaturatedSupersaturated:: more solute has been dissolved than is normally possible

Saturated: Saturated: the maximum amount of solute has been dissolved in the solvent

Unsaturated: Unsaturated: more solute can be dissolved in the solvent

A solution can be described as:

http://boyles.sdsmt.edu/supersat/

AlexanderOnly.asx

25Solubility GraphsSolubility Graphs

Solubility of KCL

0

10

20

30

40

50

60

0 20 40 60 100

Supersaturated

Unsaturated

SaturatedSaturated

Unsaturated

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Any point directly on the line = Saturated

Any point below the line = Unsaturated

Shows the relationship between temperature and solubilityShows the relationship between temperature and solubility

27Dissolving Rate Dissolving Rate

Def. – The amount of time required for a solvent to dissolve a particular solute

“Speed of dissolving”

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Dissolving Rates Dissolving Rates (Solid in a (Solid in a

Liquid &Liquid & Gas in a Liquid) Gas in a Liquid)

29Three Factors Affecting Dissolving Three Factors Affecting Dissolving Rate of a Rate of a Solid into a LiquidSolid into a Liquid::

1.1.TemperatureTemperature

2.2. StirringStirring

3.3. Surface Surface AreaArea

30TemperatureTemperature Increasing the temperature

causes an increase in kinetic energy of the solid solute and liquid solvent particles

As the particles move faster, they collide into each other more, thereby increasing the DISSOLVING RATE

31StirringStirringStirring also increases

dissolving rate

Stirring causes an increase in collisions between the particles in a solution

32Surface Area Def. – A measure of how much

exposed area a substance has Breaking, crushing, etc. are ways to

increase the Surface Area Increasing surface area allows more

solute to come into contact with the solvent; increases dissolving rate

VS.

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PressurePressure has the greatest has the greatest effect on the solubility of a effect on the solubility of a

gas in a liquid! gas in a liquid!

Depends on:Depends on:

1.1. Pressure = solubilityPressure = solubility

2.2. Temperature= solubilityTemperature= solubility

3.3. Stirring = solubilityStirring = solubility

35EffervescenceEffervescence The escape of a gas from a liquid

solution

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Day 4 – Water, Day 4 – Water, Electrolytes, Electrolytes,

and Ionic and Ionic SolutionsSolutions

Day 4 – Water, Day 4 – Water, Electrolytes, Electrolytes,

and Ionic and Ionic SolutionsSolutions

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WaterWater is a polar is a polar molecule that can molecule that can

dissolve many dissolve many solutessolutes..

HO

H

-

+ +

HO

H

-

+ +

Hydrogen BondsHydrogen Bonds: the (+) end of one

water molecule attracts a (-) end of

another.

38Polar MoleculesPolar Molecules Def. – molecules with

‘charged’ regions due to the electronegativity of the elements Compare hydrogen and

oxygen in the water molecule

One side of a water molecule is slightly negative and the other is slightly positive.

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Polar Polar solventssolvents dissolvedissolve polarpolar solutes.solutes.

Is oil polar????????Is oil polar????????

Why do you Why do you need soap to need soap to clean butter clean butter off a knife?off a knife?

41“Like Dissolves Like”

The charged ends of a polar solvent can separate the charged ends of a polar solute.

Nonpolar molecules – have an equal sharing of electrons between atoms

+-

Is vinegar polar or non-polar?Is salt polar or non-polar?

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IonizationIonization The formation of ions

by solvent as it separates the solute particles in a solution

When you pour NaCl (salt) into water, ions are formed

Na+ or Cl-

NaNa++ClCl--

NaNa++

ClCl--

NaNa++

ClCl--

NaNa++ClCl--

NaNa++

ClCl--

ClCl--NaNa++

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45ElectrolytesElectrolytes A solution in which the

solute has dissolved to create ions.

These dissolved ions allow the solution to conduct electricity.

46Types of Electrolytes NONELECTROLYTENONELECTROLYTE –

formed by solutes that DO NOT dissociate into ions in solution

STRONG ELECTROLYTESTRONG ELECTROLYTE – formed by solutes that COMPLETELY dissociate in solution

WEAK ELECTROLYTEWEAK ELECTROLYTE – formed by solutes that DO NOT COMPLETELY dissociate in solution

47Why is it dangerous to use electric appliances around

bathwater?

Distilled Water is pure water with NO dissolved salts or minerals.

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