SolutionsSolutions

Chapter 15 & 16Chapter 15 & 16ChemistryChemistry

5/285/28 Do NowDo Now

Create a three circle venn diagram that Create a three circle venn diagram that compares and contrasts the 3 examples of compares and contrasts the 3 examples of mixturesmixtures (Solutions, Suspensions, Colloids) (Solutions, Suspensions, Colloids)

Making solutionsMaking solutionsSolute: Dissolved particles

Solvents: The thing that does the dissolving.

Solution: A homogenous mixture that contains solutes dissolved in solvents.

Uniform throughout

SolutionsSolutions

HomogeneousHomogeneous 0.01 – 1 nm solute particle; atoms, ions, 0.01 – 1 nm solute particle; atoms, ions,

moleculesmolecules Does not separate on standingDoes not separate on standing Cannot be separated by filtrationCannot be separated by filtration No light scatteringNo light scattering

ColloidsColloids

HeterogeneousHeterogeneous 1 – 1000 nm dispersed particles; particles 1 – 1000 nm dispersed particles; particles

or large moleculesor large molecules Does not separate on standingDoes not separate on standing Cannot be separated by filtrationCannot be separated by filtration Scatters light (Tyndall Effect)Scatters light (Tyndall Effect)

SuspensionSuspension

HeterogeneousHeterogeneous Over 1000 nm suspended particles; large Over 1000 nm suspended particles; large

particles or aggregatesparticles or aggregates Particles settle outParticles settle out Can be separated by filtrationCan be separated by filtration May scatter light, but not transparentMay scatter light, but not transparent

ColloidsColloids

First discovered: GluesFirst discovered: Glues

The particles are spread throughout the The particles are spread throughout the dispersion medium (solid, liquid, gas).dispersion medium (solid, liquid, gas).

Cloudy or milky in appearance when Cloudy or milky in appearance when concentratedconcentrated

Look clear or almost clear when dilutedLook clear or almost clear when diluted

ColloidsColloids

Dispersed PhaseDispersed Phase State of matter that is in State of matter that is in

between the outer edge.between the outer edge. Interior phaseInterior phase

Dispersed MediumDispersed Medium Phase of matter it Phase of matter it

appears to be inappears to be in

Tyndall EffectTyndall Effect

Brownian MotionBrownian Motion Chaotic MovementChaotic Movement

Flashes of light, or scintillations, are seen when Flashes of light, or scintillations, are seen when colloids are studied under a microscope. colloids are studied under a microscope.

Caused by particles reflecting and scattering the light Caused by particles reflecting and scattering the light more erratically. more erratically.

http://galileo.phys.virginia.edu/classes/109N/more_stuhttp://galileo.phys.virginia.edu/classes/109N/more_stuff/Applets/brownian/brownian.htmlff/Applets/brownian/brownian.html

CoagulationCoagulation Colloidal particles tend to stay suspended Colloidal particles tend to stay suspended

because they become charged by absorbing because they become charged by absorbing ions from the dispersing medium onto their ions from the dispersing medium onto their surface.surface. Some positively charged, some negatively charged.Some positively charged, some negatively charged.

Destroying a colloidal systemDestroying a colloidal system Adding ions having a charge opposite to that of the Adding ions having a charge opposite to that of the

colloidal particlescolloidal particles• They neutralize the charged colloidal particlesThey neutralize the charged colloidal particles• Particles clump together to form heavier aggregates and Particles clump together to form heavier aggregates and

precipitate from the dispersionprecipitate from the dispersion

EmulsionsEmulsions

A colloidal dispersion of a liquid in a liquid.A colloidal dispersion of a liquid in a liquid. Emulsifying agent is essential for the Emulsifying agent is essential for the

formation of an emulsionformation of an emulsion• Ex. Oils and greases are not soluble in waterEx. Oils and greases are not soluble in water

• Adding soap or detergent to water allows for Adding soap or detergent to water allows for mixtures to mixmixtures to mix

• MayonnaiseMayonnaise Heterogeneous mixture of oil and vinegarHeterogeneous mixture of oil and vinegar

• Egg yolk acts as emulsifying agentEgg yolk acts as emulsifying agent

ElectrolytesElectrolytes

A compound that A compound that conducts electric current conducts electric current when it is in an aqueous when it is in an aqueous solution or in the molten solution or in the molten state.state. All ionic compounds All ionic compounds

(dissociate into ions)(dissociate into ions)

Solvation ProcessSolvation ProcessProcess by which the positive and negative ions of an ionic solid become surrounded by solvent molecules.

NonelectrolytesNonelectrolytes

A compound that does not conduct an A compound that does not conduct an electric current in either aqueous solution electric current in either aqueous solution or the molten state.or the molten state.

Many molecular compounds are not Many molecular compounds are not electrolytes (no ions).electrolytes (no ions). Sugar (sucrose), rubbing alcohol (2-propanol)Sugar (sucrose), rubbing alcohol (2-propanol)

Review on your own (Chp. 15)Review on your own (Chp. 15)

Surface TensionSurface Tension Hydrogen BondingHydrogen Bonding Vapor PressureVapor Pressure HydratesHydrates DeliquescentsDeliquescents

SolutionsSolutions

Chapter 16Chapter 16Sections 1 - 4Sections 1 - 4

Using the pictures as a model….Using the pictures as a model…. Come up with a definition of the following Come up with a definition of the following

terms:terms: SaturatedSaturated UnsaturatedUnsaturated SupersaturatedSupersaturated

A little earth science never hurts anyone.

Another example that you learned

everything in Earth Science

already

Solubility CurvesSolubility Curves

Saturated

Unsaturated

Oversaturated

Factors Affecting SolubilityFactors Affecting Solubility

TemperatureTemperature Most solidsMost solids

• Substance solubility increases with TemperatureSubstance solubility increases with Temperature

Mineral deposits a result of cooling of solution of mineral water.

Cooling water holds less minerals

Factors Affecting SolubilityFactors Affecting Solubility

PressurePressure Little affect on solids and liquidsLittle affect on solids and liquids Strong influence on GasesStrong influence on Gases

MolarityProblem: Calculate the molarity of a solution containing 100 g of KCl in 500 ml of water.

1 mol = 1.34 mol

.5 liters

100 g74.6 g

K 1 x 39.1 = 39.1

Cl 1 x 35.5 = 35.5

74.6

Molarity =1.34 moles

2.68 M

M = moles liters

MolarityMolarity

The number of moles of solute in one liter The number of moles of solute in one liter of solutionof solution

Molarity = # of moles of soluteMolarity = # of moles of solute -------------------------------------------------------- # of liters of solution# of liters of solution

Units - MUnits - M

Percent by MassPercent by Mass

Percent by mass of a solute in solution is Percent by mass of a solute in solution is the number of grams of solute dissolved in the number of grams of solute dissolved in 100 grams of solution.100 grams of solution.

% (m/m) =% (m/m) = mass of solute / mass of solution x 100mass of solute / mass of solution x 100 Mass of solute + Mass of solventMass of solute + Mass of solvent

% (v/v) =% (v/v) = volume of solute / volume of solution x 100volume of solute / volume of solution x 100 volume of solute + volume of solventvolume of solute + volume of solvent

% Mass and % Volume Products% Mass and % Volume Products

3 %

Colligative PropertiesColligative Properties Property that depends on the number of Property that depends on the number of

solute particles but is independent of their solute particles but is independent of their naturenature

Adding Adding NonvolatileNonvolatile solute solute ((little tendency to little tendency to become a gas under existing conditionsbecome a gas under existing conditions)) Lowers the vapor pressure of solventLowers the vapor pressure of solvent Lowers the freezing point of solutionLowers the freezing point of solution Raises the boiling point of solutionRaises the boiling point of solution

Vapor-Pressure LoweringVapor-Pressure Lowering Vapor pressureVapor pressure

Pressure exerted by a vapor that is in dynamic Pressure exerted by a vapor that is in dynamic equilibrium with its liquid in a closed system.equilibrium with its liquid in a closed system.

VolatilityVolatility Ease of vaporizationEase of vaporization Glucose, sodium chlorideGlucose, sodium chloride

• When dissolved in a solvent, the vapor pressure of the When dissolved in a solvent, the vapor pressure of the solution is lower than the vapor pressure of the pure solvent.solution is lower than the vapor pressure of the pure solvent.

Colligative Property:Vapor Pressure lowering

MolalityMolality

The concentration of a solution expressed The concentration of a solution expressed in moles of solute per kilogram of solventin moles of solute per kilogram of solvent

Molality = # of moles soluteMolality = # of moles solute------------------------------------------------------ mass of solvent (kg)mass of solvent (kg)

Units - mUnits - m

Freezing Point DepressionFreezing Point Depression A colligative propertyA colligative property The difference in temperature between the freezing point The difference in temperature between the freezing point

of a solution and the freezing point of the pure solvent.of a solution and the freezing point of the pure solvent.

ΔΔTTf = f = KKff x d.f. x x d.f. x mm

ΔΔTTf = Freezing point depressionf = Freezing point depression

mm = = molalitymolalityKKf = molal freezing-point depression constantf = molal freezing-point depression constant

For Water (1.86For Water (1.86°C/°C/mm))

d.f. = d.f. = Dissociation Factor Dissociation Factor (covalents it is one, Ionic it depends on ions it dissociates into)(covalents it is one, Ionic it depends on ions it dissociates into)

Boiling Point ElevationBoiling Point Elevation Boiling point = vapor pressure equals atmospheric Boiling point = vapor pressure equals atmospheric

pressurepressure Change in either causes a change in boiling pointChange in either causes a change in boiling point

Boiling point elevation of 1 molal solution of any Boiling point elevation of 1 molal solution of any molecular solute in water is 0.512 degrees Celsiusmolecular solute in water is 0.512 degrees Celsius

ΔΔTTb = b = KKbb x d.f. x x d.f. x mm

ΔΔTTb = Boiling Point Elevationb = Boiling Point Elevation

m = m = molalitymolalityKKb = molal boiling-point elevation constantb = molal boiling-point elevation constant

For Water (0.512For Water (0.512°C/°C/mm))

d.f. = d.f. = Dissociation Factor Dissociation Factor (covalents it is one, Ionic it depends on ions it dissociates into)(covalents it is one, Ionic it depends on ions it dissociates into)

Formation of a SolutionFormation of a Solution

Cl-

Na+ Cl-Na+

H2O

salt

Na+

Cl-

solute

Dissolvedsolute

HydrationSolvent

Solvation

Solubility RulesSolubility Rules