Chapter 12-13:Chapter 12-13:MixturesMixtures and and Aqueous Aqueous

SolutionsSolutions

What are they?What are they?

Where do we find them?Where do we find them?

How do we describe them?How do we describe them?

We use solutions all the time

Soluble versus insolubleSoluble versus insoluble• Some solids are soluble in water, ie: table Some solids are soluble in water, ie: table

salt, NaCl. salt, NaCl. Soluble Soluble means: means: able to be able to be dissolveddissolved..

• Soluble Soluble ionic solidsionic solids (made of cation and (made of cation and anion) anion) dissociate into their ionsdissociate into their ions in water. in water.

• Soluble Soluble covalent solidscovalent solids (like sugar) (like sugar) dissolve because they are dissolve because they are relatively relatively polarpolar..

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• In a solution, the dissolved particles In a solution, the dissolved particles cannot be easily seen or separated from cannot be easily seen or separated from the solution.the solution.

• Alloys are solutions of metals!Alloys are solutions of metals!

Parts of a Parts of a solutionsolution• The The dissolving mediumdissolving medium is the is the solventsolvent

(what does the dissolving)(what does the dissolving)

• The The dissolved substancedissolved substance is the is the solutesolute (what gets dissolved)(what gets dissolved)

• The The solute solute andand solventsolvent togethertogether form form the the solutionsolution..

• Solvents and solutes can be any Solvents and solutes can be any phasephase..

solution

Special types of mixtures - Special types of mixtures - SuspensionsSuspensions

• SuspensionsSuspensions– mixtures where the solutes mixtures where the solutes

particles are particles are very largevery large, so they , so they don’tdon’t completely completely dissolvedissolve into into their solvent.their solvent.

• Solute particles will settle out Solute particles will settle out of the solution if left of the solution if left undisturbed. – this creates two undisturbed. – this creates two phasesphases..

• Muddy water and Italian salad Muddy water and Italian salad dressing are good examples of dressing are good examples of suspensions.suspensions.

Special types of mixtures - Special types of mixtures - ColloidsColloids

• ColloidsColloids– mixtures where the solute particle is mixtures where the solute particle is smaller smaller

than particles in a suspensionthan particles in a suspension, but , but not small not small enough to dissolveenough to dissolve..

• Colloids have two Colloids have two phasesphases::Dispersed phaseDispersed phase – the – the solutesoluteDispersing mediumDispersing medium – the – the solventsolvent..

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ColloidsColloids• Mayonnaise and hair gel are good Mayonnaise and hair gel are good

examples of colloids.examples of colloids.

• There are 7 types of colloids, found on There are 7 types of colloids, found on page 404…page 404…

7 Types of Colloids7 Types of ColloidsPage 404

Two groups of colloids:

Heterogeneous colloids – two phases are clearly seen

Homogeneous colloids – appears to be one phase

Colloid TypeColloid Type PhasesPhases ExampleExample

SolSol solid in liquid, liquid substancesolid in liquid, liquid substance PaintPaint

GelGel solid in liquid, solid substancesolid in liquid, solid substance GelatinGelatin

FoamFoam gas in liquidgas in liquid Whipped creamWhipped cream

Liquid Liquid EmulsionEmulsion

liquid in liquidliquid in liquid Milk, mayonnaiseMilk, mayonnaise

Solid Solid EmulsionEmulsion

liquid in solidliquid in solid Cheese, butterCheese, butter

Solid AerosolSolid Aerosol solid in gassolid in gas SmokeSmoke

Liquid Liquid AerosolAerosol

liquid in gasliquid in gas Clouds, fogClouds, fog

The Tyndall EffectThe Tyndall Effect

The Tyndall effect allows us to distinguish between solutions, colloids, and suspensions.

It works by shining a beam of light into the mixture. If…

John Tyndall, Brittish, c1860

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Bires, 2005 Slide 10

Results of Tyndall EffectResults of Tyndall Effect• Light doesn’t pass through

– the mixture is a suspension or a heterogeneous colloid.

• Light passes through unobstructed– the mixture is a solution.

• Light passes, but the beam can be seen in the mixture– the mixture is a homogeneous colloid

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Bires, 2005 Slide 11

The Tyndall EffectThe Tyndall Effect

ElectrolytesElectrolytes• ElectrolytesElectrolytes

– Solutions that Solutions that conduct electricityconduct electricity..

• Ionic solutionsIonic solutions are are electrolyteselectrolytes..

• Covalent solutionsCovalent solutions are are nonelectrolytesnonelectrolytes..

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Bires, 2005 Slide 13

What do you think?What do you think?

Is saltwater (NaCl in water) an electrolyte?Is saltwater (NaCl in water) an electrolyte?

Is sugar water (CIs sugar water (C66HH1212OO66 in water) an in water) an electrolyte?electrolyte?

Conductivity tester (meter)Conductivity tester (meter)– can tell us if a solution is an electrolyte, and can tell us if a solution is an electrolyte, and

sometimes, how sometimes, how strongstrong an electrolyte is. an electrolyte is.

SolubilitySolubility• SolubilitySolubility

– The extent to which a solute will dissolve in a The extent to which a solute will dissolve in a solvent. solvent. (how (how muchmuch solute will dissolve) solute will dissolve)

• High solubilityHigh solubility– large amounts of solute will dissolve in a large amounts of solute will dissolve in a

solventsolvent

• Low solubilityLow solubility– only small amounts of solute will dissolveonly small amounts of solute will dissolve

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Bires, 2005 Slide 15

Warm UpWarm Up

I am collecting: I am collecting:

Thermo Article Analysis (get it to me Thermo Article Analysis (get it to me by by Monday if it isn’t done!)Monday if it isn’t done!)

Book Notes- 16.1 and 10.4Book Notes- 16.1 and 10.4

Thermo ReviewThermo Review

Last minute questions?Last minute questions?

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Bires, 2005 Slide 16

SolubilitySolubility• Increasing temperature Increasing temperature increasesincreases the the

solubility of solubility of solidssolids in liquids. in liquids.

• Increasing temperature Increasing temperature decreasesdecreases the the solubility of solubility of gasesgases in liquids! … in liquids! …

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Reading Solubility CurvesReading Solubility Curves

Solid-LiquidSolid-Liquid solubility with solubility with temperaturetemperature

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Gas-LiquidGas-Liquid solubility with solubility with temperaturetemperature

Gases in liquidsGases in liquids• In addition to cold In addition to cold

temperatures, temperatures, high high pressures increase pressures increase solubilitysolubility of gases of gases in liquids.in liquids.

• Henry’s LawHenry’s Law::– solubility of a gas in solubility of a gas in

a liquid increases a liquid increases with increasing with increasing pressure of that gas pressure of that gas above the liquid.above the liquid.

Like Dissolves Like!Like Dissolves Like!• Some solvents are Some solvents are polarpolar, having , having partialpartial negative negative

and partial positive endsand partial positive ends. (. (HH22OO))

• Other solvents are Other solvents are nonpolarnonpolar, having no “+” “-” , having no “+” “-” polespoles

• Polar solutes tend to dissolve well in polar Polar solutes tend to dissolve well in polar solventssolvents……

• Nonpolar solutes tend to dissolve well into Nonpolar solutes tend to dissolve well into nonpolar solventsnonpolar solvents..

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Bires, 2005 Slide 22

Like Dissolves LikeLike Dissolves Like

Water is very polar. Does it dissolve polar Water is very polar. Does it dissolve polar substances or non polar substance?substances or non polar substance?

SaturationSaturation• Saturated SolutionSaturated Solution

– solution has as much solute in it as it will solution has as much solute in it as it will allow (equal to solubility)allow (equal to solubility)

• Unsaturated SolutionUnsaturated Solution– more solute can still dissolve into solution more solute can still dissolve into solution

(less than solubility)(less than solubility)

• Supersaturated SolutionSupersaturated Solution– too much solute in solution-some will fall out too much solute in solution-some will fall out

(more than solubility)(more than solubility)

• We express the We express the quantitative amountquantitative amount of of solute in a solution with solute in a solution with concentrationconcentration … …

Solid-LiquidSolid-Liquid solubility with solubility with temperaturetemperature

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Warm UPWarm UP1.1. Which solute is more Which solute is more

soluble at 30C?soluble at 30C?

2.2. What is the solubility What is the solubility of KCl at 80 C?of KCl at 80 C?

3.3. How much would How much would you add to 20g of you add to 20g of KCl in 200g of water KCl in 200g of water to saturate the to saturate the solution?solution?

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Bires, 2005 Slide 26

What is the general rule for What is the general rule for determining solubility?determining solubility?

SolventsSolvents

WaterWater

CClCCl44

CC22HH66O- ethanolO- ethanol

SolutesSolutes

II22

NaClNaCl

KNOKNO33

BrBr22

BenzeneBenzene

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Bires, 2005 Slide 27

Which would be electrolytes when Which would be electrolytes when dissolved in water?dissolved in water?

II22

NaClNaCl

KNOKNO33

BrBr22

BenzeneBenzene

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How did you do on the HW?How did you do on the HW?

Get into your small groups and compare Get into your small groups and compare answers!answers!

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Solubility of KNOSolubility of KNO33 Lab Lab

1.1.Number your test tubes 1 – 4.Number your test tubes 1 – 4.

2.2.Mass 2.0g, 4.0g, 6.0g and 8.0g into the Mass 2.0g, 4.0g, 6.0g and 8.0g into the test tubes… the actual amt doesn’t test tubes… the actual amt doesn’t matter as long as you record the values.matter as long as you record the values.

3.3.Place 5 ml of distilled water into your Place 5 ml of distilled water into your test tubes.test tubes.

4.4.Heat them all up…and wait for them to Heat them all up…and wait for them to dissolve.dissolve.

5.5.Record the temperature where you see Record the temperature where you see the crystals reforming (saturation point). the crystals reforming (saturation point).

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Warm Up- Use your Solubility Curve WS to answer Warm Up- Use your Solubility Curve WS to answer the questions on the half sheet!the questions on the half sheet!

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Would the following be soluble Would the following be soluble in water? Would they be in water? Would they be

electrolytes?electrolytes?Hexane- CHexane- C66HH1414

MgClMgCl22

NaOHNaOH

COCO22

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Bires, 2005 Slide 32

DemoDemo

Classify the following as a solution, colloid Classify the following as a solution, colloid or suspension.or suspension.

1. 1. NaCl in water?NaCl in water?

2. Clay (a compound with Si, C and H)2. Clay (a compound with Si, C and H)

3. Na3. Na22COCO33

4. Sugar in water (C4. Sugar in water (C66HH1212OO66))

55. . Corn Starch (a hydrocarbon) in water Corn Starch (a hydrocarbon) in water

Electrolyte or nonelectrolyte?Electrolyte or nonelectrolyte?

Concentration - Concentration - MolarityMolarity• The “Stoichiometry” of SolutionsThe “Stoichiometry” of Solutions

• ConcentrationConcentration– the the quantitativequantitative amount of solute present in amount of solute present in

a solutiona solution

• MolarityMolarity ( (MM) – ) – moles/litermoles/liter– number of moles solute in liters of solutionnumber of moles solute in liters of solution

)(

)()(

Lsolutionofvolume

molsoluteofamountMMolarity

Try these Molarity questionsTry these Molarity questions• What is the concentration [in Molarity] when 3 What is the concentration [in Molarity] when 3

moles of NaCl are dissolved in 2 Liters of water?moles of NaCl are dissolved in 2 Liters of water?

• How much (in liters) of a 0.1 M solution do you How much (in liters) of a 0.1 M solution do you need to get 2 moles of solute?need to get 2 moles of solute?

• How many moles of NaOH are present in 300mL How many moles of NaOH are present in 300mL of a 1M solution?of a 1M solution?

• How many grams of HCl are found in 100mL of How many grams of HCl are found in 100mL of a 2M solution?a 2M solution?

1.5 M “molar”

20 L

.3 moles

7.2 grams

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Work on the 1Work on the 1stst 3 problems- Front and 3 problems- Front and Back… Back…

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Warm UpWarm Up

Are the following substances soluble in water?Are the following substances soluble in water?

Chlorine- ClChlorine- Cl22

CFCF33II

NaCONaCO33

Would they be electrolytes or nonelectrolytes?Would they be electrolytes or nonelectrolytes?

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Questions on Molarity Packet?Questions on Molarity Packet?

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Are all Ionic Compounds Are all Ionic Compounds Soluble?Soluble?

Let’s look at the solubility rules…Let’s look at the solubility rules…

These are very important when looking at These are very important when looking at what happens in double replacement what happens in double replacement

reactions.reactions.

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Solubility LabSolubility Lab

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Warm Up: Predict the products, balance Warm Up: Predict the products, balance the equation and determine the states of the equation and determine the states of

matter matter

NaCl + CaNONaCl + CaNO33

LiSOLiSO44 + SrCl + SrCl22

BaClBaCl22 + H + H22SS

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Solubility Rule LabSolubility Rule Lab

Questions on the lab??Questions on the lab??

Did you…Did you…

Write the first 30 equations and Write the first 30 equations and indicate the indicate the states of matter?states of matter?

Identify ALL the precipitates?Identify ALL the precipitates?

Answer the questions using complete Answer the questions using complete sentences?sentences?

DissociationDissociation and Ions Present and Ions Present• DissociationDissociation = a salt dissolving into its = a salt dissolving into its

ions:ions:

• How many moles of ions are in a solution How many moles of ions are in a solution of 1 mole of NaCl?of 1 mole of NaCl?

• How many moles of ions are in solutions How many moles of ions are in solutions of 1 mole of each of the following?:of 1 mole of each of the following?:

)()()( aqaqs ClNaNaCl

24

24 SOCuCuSO

2332 2 CONaCONa

32

23 2)( NOMgNOMg

Net Ionic EquationsNet Ionic Equations• When we write a When we write a balanced chemical balanced chemical

equationequation, we show all species present (all , we show all species present (all reactants and all products):reactants and all products):

• In a In a net ionic equationnet ionic equation, we show only , we show only precipitates formed, and the reactants precipitates formed, and the reactants that form them:that form them:

• The chemicals that The chemicals that stay ionsstay ions are called are called spectator ionsspectator ions, , And are left outAnd are left out ( (NaNa++, , NONO33

--))

)(3)()()(3 aqsaqaq NaNOAgClNaClAgNO

)()()( saqaq AgClClAg Remember to Balance

Net Ionic Equation PracticeNet Ionic Equation Practice• Write the net ionic equations for the Write the net ionic equations for the

following:following: )()( )()(23 ntdisplacemedoubleKINOPb aqaq

)(2)()(2

saqaq PbIIPb

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Net Ionic Equation PracticeNet Ionic Equation Practice• Write the net ionic equations for the Write the net ionic equations for the

following:following:

)()(2)(2 ntdisplacemedoubleSKNiCl aqaq

)()(2

)(2

saqaq NiSSNi

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Bires, 2005 Slide 46

Net Ionic Equation PracticeNet Ionic Equation Practice• Write the net ionic equations for the Write the net ionic equations for the

following:following:)()(32)(2 ntdisplacemedoubleCONaBaCl aqaq

)(3)(23)(

2saqaq BaCOCOBa

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Bires, 2005 Slide 47

Now you are ready to work on Now you are ready to work on the homework WS…the homework WS…

Strong/Weak ElectrolytesStrong/Weak Electrolytes• Recall that a solid compound made up of Recall that a solid compound made up of

a a cationcation and and anionanion is called a is called a saltsalt..

• SaltsSalts that that dissolve completelydissolve completely into their into their ions when put in water ions when put in water dissociate dissociate completelycompletely..

• Salts that Salts that dissociate completelydissociate completely form form strong electrolytesstrong electrolytes – solutions that – solutions that conduct electricity wellconduct electricity well..

• Some salts only Some salts only partially dissociatepartially dissociate, , forming forming weak electrolytesweak electrolytes – solutions that – solutions that conduct electricity, but do so poorlyconduct electricity, but do so poorly..

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Bires, 2005 Slide 49

Quiz…Quiz…

Solution PreparationSolution PreparationBy solid dissolving:By solid dissolving:1. Calculate how many grams are needed to 1. Calculate how many grams are needed to create our volume of our desired molarity create our volume of our desired molarity solutionsolution

2. Weigh out that mass, and add it to a 2. Weigh out that mass, and add it to a volumetric flaskvolumetric flask

3. add some water and allow to dissolve3. add some water and allow to dissolve

4. add water to the desired volume4. add water to the desired volume

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Let’s make 1.0L of a 2.0M NaCl solution.Let’s make 1.0L of a 2.0M NaCl solution.

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Try these!!Try these!!

How many grams of sodium chloride are How many grams of sodium chloride are needed to make a 1.3M solution?needed to make a 1.3M solution?

How much sodium hydroxide is needed to How much sodium hydroxide is needed to make a 4.6M solution?make a 4.6M solution?

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Bires, 2005 Slide 53

Solution PreparationSolution PreparationBy By dilutiondilution of a standard solution: of a standard solution:

1.1.Use the relationship Use the relationship MM11VV11==MM22VV22

2. Calculate volume of the 2. Calculate volume of the ““standard solution”standard solution” to use to get to use to get desired volume of desired volume of desired molarity desired molarity solutionsolution..

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Bires, 2005 Slide 54

Try these…Try these…1.1.How much 12 M stock solution is needed How much 12 M stock solution is needed

to make 500.mL of a 3.5M solution?to make 500.mL of a 3.5M solution?

2.2.What is the molarity of a stock solution What is the molarity of a stock solution where you used 200. ml to make 0.5 L of where you used 200. ml to make 0.5 L of a 2.5M HCl solution. a 2.5M HCl solution.

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Bires, 2005 Slide 55

Solution FormationSolution Formation• The nature of the solvent and solute The nature of the solvent and solute

affects whether a substance will dissolveaffects whether a substance will dissolve

• Other factors determine how fast a Other factors determine how fast a soluble substance dissolvessoluble substance dissolves

– Agitation (shaking)Agitation (shaking)– TemperatureTemperature

– Solute particle sizeSolute particle size