Solids, Liquids and Solids, Liquids and SolutionsSolutions

Intermolecular ForcesIntermolecular Forces

Dipole-dipole attractionDipole-dipole attractionHydrogen bondsHydrogen bondsDispersion forcesDispersion forces

Forces of attraction between different molecules rather than bonding forces within the same molecule.

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Forces and PhasesForces and Phases

o Substances with very little Substances with very little intermolecular attraction exist as intermolecular attraction exist as gasesgases

o Substances with strong Substances with strong intermolecular attraction exist as intermolecular attraction exist as liquidsliquids

o Substances with Substances with very strongvery strong intermolecular (or ionic) attraction intermolecular (or ionic) attraction exist as solidsexist as solids

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Phase Differences

SolidSolid – definite volume and shape; particles packed in fixed positions; particles are not free to moveLiquidLiquid – definite volume but indefinite shape; particles close together but not in fixed positions; particles are free to move

GasGas – neither definite volume nor definite shape; particles are at great distances from one another; particles are free to move

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Three Phases of Matter

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Effect of Pressure on Boiling Effect of Pressure on Boiling PointPoint

Boiling Point of Water at Various Locations

Location Feet above sea level

Patm (kPa) Boiling Point (C)

Top of Mt. Everest, Tibet 29,028 32 70

Top of Mt. Denali, Alaska 20,320 45.3 79

Top of Mt. Whitney, California

14,494 57.3 85

Leadville, Colorado 10,150 68 89

Top of Mt. Washington, N.H. 6,293 78.6 93

Boulder, Colorado 5,430 81.3 94

Madison, Wisconsin 900 97.3 99

New York City, New York 10 101.3 100

Death Valley, California -282 102.6 100.3

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Types of SolidsTypes of SolidsCrystalline SolidsCrystalline Solids: highly regular : highly regular

arrangement of their components [table arrangement of their components [table salt (NaCl), pyrite (FeSsalt (NaCl), pyrite (FeS22)].)].

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Representation of Representation of Components in a Crystalline Components in a Crystalline

SolidSolidLatticeLattice: A 3-: A 3-dimensional system of dimensional system of points designating the points designating the centers of components centers of components (atoms, ions, or (atoms, ions, or molecules) that make molecules) that make up the substance.up the substance.

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Unit CellThe smallest portion of a crystal lattice that shows the three-dimensional pattern of the entire lattice

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Packing in MetalsPacking in Metals

ModelModel: Packing uniform, hard : Packing uniform, hard spheres to best use available space. spheres to best use available space. This is called This is called closest packingclosest packing. Each . Each atom has 12 nearest neighbors.atom has 12 nearest neighbors.

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Types of SolidsTypes of Solids

Amorphous Amorphous solidssolids: : considerable considerable disorder in their disorder in their structures structures (glass and (glass and plastic).plastic).

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Water phase changesWater phase changes

Temperature remains __________during a phase change.

constant

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Phase DiagramPhase DiagramRepresents phases as a function of Represents phases as a function of temperature and pressure.temperature and pressure.Critical temperatureCritical temperature: temperature : temperature above which the vapor can not be above which the vapor can not be liquefied.liquefied.Critical pressureCritical pressure: pressure required to : pressure required to liquefy liquefy ATAT the critical temperature. the critical temperature.Critical pointCritical point: critical temperature and : critical temperature and pressure (for water, pressure (for water, TTcc = 374°C and 218 = 374°C and 218 atm).atm).

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Phase changes by NamePhase changes by Name

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WaterWaterWaterWater

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Carbon dioxideCarbon dioxideCarbonCarbondioxidedioxide

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CarbonCarbonCarbonCarbon

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SulfurSulfur

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Classification of MatterClassification of MatterSolutions are homogeneous mixtures

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SoluteSoluteA solute is the dissolved substance in a solution.

A solvent is the dissolving medium in a solution.

SolvenSolventt

Salt in salt water Sugar in soda drinks

Carbon dioxide in soda drinks

Water in salt water Water in soda

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SolventsSolvents

Solvents at the hardware store19

Dissolution of sodium Dissolution of sodium ChlorideChloride

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Concentrated vs. DiluteConcentrated vs. Dilute

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Heat of SolutionHeat of SolutionThe Heat of Solution is the amount of heat energy absorbed (endothermic) or released (exothermic) when a specific amount of solute dissolves in a solvent.

SubstancSubstancee

Heat of Heat of Solution Solution

(kJ/mol)(kJ/mol)NaOHNaOH -44.51-44.51

NHNH44NONO33 +25.69+25.69

KNOKNO33 +34.89+34.89

HClHCl -74.84-74.84

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The ammeter measures the flow of electrons (current) through the circuit.

If the ammeter measures a current, and the bulb glows, then the solution conducts.

If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.

Electrolytes vs. Electrolytes vs. NonelectrolytesNonelectrolytes

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An electrolyte is:

A substance whose aqueous solution conducts an electric current.

A nonelectrolyte is:

A substance whose aqueous solution does not conduct an electric current.

Try to classify the following substances as electrolytes or nonelectrolytes…

Definition of Electrolytes and Definition of Electrolytes and NonelectrolytesNonelectrolytes

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1.Pure water2.Tap water3.Sugar solution4.Sodium chloride solution5.Hydrochloric acid solution6.Lactic acid solution7.Ethyl alcohol solution8.Pure sodium chloride

Electrolytes?Electrolytes?

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ELECTROLYTES: NONELECTROLYTES:

Tap water (weak)

NaCl solution

HCl solution

Lactate solution (weak)

Pure water

Sugar solution

Ethanol solution

Pure NaCl

But why do some compounds conduct electricity insolution while others do not…?

Answers to ElectrolytesAnswers to Electrolytes

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Suspensions and Suspensions and ColloidsColloids

Suspensions and colloids are NOT solutions. Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred.

Colloids: The particle is intermediate in size between those of a suspension and those of a solution.

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Types of Colloids

Examples Dispersing Medium

Dispersed Substance

Colloid Type

Fog, aerosol sprays Gas Liquid Aerosol

Smoke, airborne bacteria Gas Solid Aerosol

Whipped cream, soap suds

Liquid Gas Foam

Milk, mayonnaise Liquid Liquid Emulsion

Paint, clays, gelatin Liquid Solid Sol

Marshmallow, Styrofoam Solid Gas Solid foam

Butter, cheese Solid Liquid Solid emulsion

Ruby glass Solid Solid Solid sol

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The Tyndall EffectThe Tyndall Effect

Colloids scatter light, making a beam visible. Solutions do not scatter light.

Which glass contains a colloid?

solutioncolloid

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Factors Effecting SolubilityFactors Effecting Solubility The solubility of MOST solids The solubility of MOST solids

increases with temperature.increases with temperature. The rate at which solids dissolve The rate at which solids dissolve

increases with increasing surface increases with increasing surface area of the solid.area of the solid.

The solubility of gases decreases The solubility of gases decreases with increases in temperature.with increases in temperature.

The solubility of gases increases The solubility of gases increases with the pressure above the with the pressure above the solution.solution.

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Therefore…Therefore…Solids tend to dissolve best when:

o Heatedo Stirredo Ground into small particles

Liquids tend to dissolve best when:o The solution is cold

o Pressure is high

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Saturation of SolutionsSaturation of Solutions A solution that contains the maximum A solution that contains the maximum

amount of solute that may be dissolved amount of solute that may be dissolved under existing conditions is under existing conditions is saturatedsaturated..

A solution that contains less solute than A solution that contains less solute than a saturated solution under existing a saturated solution under existing conditions is conditions is unsaturatedunsaturated..

A solution that contains more dissolved A solution that contains more dissolved solute than a saturated solution under solute than a saturated solution under the same conditions is the same conditions is supersaturatedsupersaturated..

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Solubility ChartSolubility Chart

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Calculations of Solution Calculations of Solution ConcentrationConcentration

ConcentrationConcentration - A measure of the amount of - A measure of the amount of

solute in a given amount of solvent or solutionsolute in a given amount of solvent or solution

Molarity - moles of solute divided by the volume of solution in liters

Parts per million – the ratio of parts (mass) of solute to one million parts (mass) of solution

Grams per liter - the mass of solute divided by the volume of solution, in liters

Percent composition - the ratio of one part of solute to one hundred parts of solution, expressed as a percent

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Colligative PropertiesColligative Properties

Colligative properties are those that depend on the concentration of particles in a solution, not upon the identity of those properties.

Boiling Point Elevation Freezing Point Depression Osmotic Pressure

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Freezing Point DepressionFreezing Point Depression

Each mole of solute particles lowers the freezing point of 1 kilogram of water by 1.86 degrees Celsius.

Kf = 1.86 C kilogram/mol

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Boiling Point ElevationBoiling Point Elevation

Each mole of nonvolatile solute particles raises the boiling point of 1 kilogram of water by 0.51 degrees Celsius.

Kb = 0.51 C kilogram/mol

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Freezing Point Depression and Freezing Point Depression and Boiling Point Elevation Boiling Point Elevation

ConstantsConstants

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Properties of AcidsProperties of Acids

Acids taste sour Acids effect indicators

Blue litmus turns red Methyl orange turns red

Acids have a pH lower than 7 Acids are proton (hydrogen ion, H+) donors Acids react with active metals, produce H2

Acids react with carbonates Acids neutralize bases

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Acids you SHOULD know:Acids you SHOULD know:

Strong Acids Weak Acids

Hydrochloric acid, HCl

Nitric acid, HNO3

Sulfuric acid, H2SO4 Phosphoric acid, H3PO4

Acetic acid, HC2H3O2

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Sulfuric AcidSulfuric Acid Highest volume production of any Highest volume production of any

chemical in the U.S.chemical in the U.S. Used in the production of paperUsed in the production of paper Used in production of fertilizersUsed in production of fertilizers Used in petroleum refiningUsed in petroleum refining

Thick clouds of sulfuric acid are a feature of the atmosphere of Venus.

(image provided by NASA)

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Nitric AcidNitric Acid• Used in the production Used in the production

of fertilizersof fertilizers• Used in the production Used in the production

of explosivesof explosives• Nitric acid is a volatile Nitric acid is a volatile

acid – its reactive acid – its reactive components evaporate components evaporate easilyeasily

• Stains proteins Stains proteins (including skin!)(including skin!)

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Hydrochloric AcidHydrochloric Acid• Used in the pickling of Used in the pickling of

steelsteel• Used to purify Used to purify

magnesium from sea magnesium from sea waterwater

• Part of gastric juice, it Part of gastric juice, it aids in the digestion aids in the digestion of proteinof protein

• Sold commercially as Sold commercially as “Muriatic acid”“Muriatic acid”

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Phosphoric Phosphoric AcidAcid

o A flavoring agent in A flavoring agent in sodassodas

o Used in the Used in the manufacture of manufacture of detergentsdetergents

o Used in the Used in the manufacture of manufacture of fertilizersfertilizers

o NotNot a common a common laboratory reagentlaboratory reagent

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Acetic AcidAcetic AcidUsed in the manufacture Used in the manufacture

of plasticsof plasticsUsed in making Used in making

pharmaceuticalspharmaceuticalsAcetic acid is the acid Acetic acid is the acid

present in vinegarpresent in vinegar

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Acids are Proton DonorsAcids are Proton Donors

Monoprotic acidsDiprotic acids Triprotic acids

HCl

HC2H3O2

HNO3

H2SO4

H2CO3

H3PO4

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Strong Acids vs. Weak AcidsStrong Acids vs. Weak Acids

Strong acids are assumed to be 100% ionized in solution (good proton donors).

Weak acids are usually less than 5% ionized in solution (poor proton donors).

HCl

H2SO4 HNO3

H3PO4 HC2H3O2 Organic acids

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Strong Acid DissociationStrong Acid Dissociation

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Weak Acid DissociationWeak Acid Dissociation

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Organic AcidsOrganic AcidsOrganic acids all contain the “carboxyl” group, sometimes several of them.

The carboxyl group is a poor proton donor, so ALL organic acids are weak acids.

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Examples of Organic AcidsExamples of Organic Acids

Citric acid in citrus fruitCitric acid in citrus fruit Malic acid in sour applesMalic acid in sour apples Deoxyribonucleic acid, DNADeoxyribonucleic acid, DNA Amino acids, the building blocks of Amino acids, the building blocks of

proteinprotein Lactic acid in sour milk and sore Lactic acid in sour milk and sore

musclesmuscles Butyric acid in rancid butterButyric acid in rancid butter

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Acids Effect IndicatorsAcids Effect Indicators

Blue litmus paper turns red in contact with an acid.

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Acids Acids Have a pH Have a pH less than less than

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Acids React with Active Acids React with Active MetalsMetals

Acids react with active metals to form salts and hydrogen gas.

Mg + 2HCl MgCl2 + H2(g)

Zn + 2HCl ZnCl2 + H2(g)

Mg + H2SO4 MgSO4 + H2(g)

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AcidsAcids React withReact with CarbonatesCarbonates

2HC2H3O2 + Na2CO3

2 NaC2H3O2 + H2O + CO2

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Effects of Acid Rain on MarbleEffects of Acid Rain on Marble(calcium (calcium carbonatecarbonate))

George Washington:BEFORE

George Washington:AFTER

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Acids Neutralize BasesAcids Neutralize Bases

HCl + NaOH NaCl + H2O

Neutralization reactions ALWAYS produce a salt and water.

H2SO4 + 2NaOH Na2SO4 + 2H2O

2HNO3 + Mg(OH)2 Mg(NO3)2 + 2H2O

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Properties of BasesProperties of Bases Bases taste bitter Bases effect indicators

Red litmus turns blue Phenolphthalein turns purple

Bases have a pH greater than 7 Bases are proton (hydrogen ion, H+) acceptors Solutions of bases feel slippery Bases neutralize acids

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Examples of BasesExamples of Bases

Sodium hydroxide (lye), NaOHSodium hydroxide (lye), NaOH Potassium hydroxide, KOHPotassium hydroxide, KOH Magnesium hydroxide, Mg(OH)Magnesium hydroxide, Mg(OH)22

Calcium hydroxide (lime), Ca(OH)Calcium hydroxide (lime), Ca(OH)22

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Bases Effect Bases Effect IndicatorsIndicators

Red litmus paper turns blue in contact with a base. Phenolphthale

in turns purple in a base.

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Bases Bases have a pH have a pH

greater greater than 7than 7

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Bases Neutralize Bases Neutralize AcidsAcids

Milk of Magnesia contains magnesium hydroxide, Mg(OH)2, which neutralizes stomach acid, HCl.

2 HCl + Mg(OH)2

MgCl2 + 2 H2O

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