Classification of MatterClassification of Matter
MatterMatter
PureSubstances
Mixtures
HomogeneousHomogeneousMixturesMixtures
HeterogeneousHeterogeneousMixturesMixtures
ElementsElements CompoundsCompounds
Heterogeneous MixturesHeterogeneous Mixtures
• See See visibly different regionsvisibly different regions– GraniteGranite
– DirtDirt
– CerealsCereals
– Oil & VinegarOil & Vinegar
• See a See a boundaryboundary– Ice cube in waterIce cube in water
Homogeneous MixturesHomogeneous Mixtures
• ParticlesParticles very smallvery small – on atomic scale – on atomic scale– Can’t see particles– Can’t sort particles– Can’t get trapped by filter– Can’t scatter light
• Particles Particles evenly distributedevenly distributed• Particles Particles do not separatedo not separate
SolutionSolution
Homogeneous mixture of 2 or Homogeneous mixture of 2 or more substances in a single more substances in a single physical statephysical state (phase) (phase)
Parts of a SolutionParts of a Solution
• SoluteSolute = dissolved substance
• SolventSolvent = dispersing medium
Identify the solute Identify the solute and solvent in each and solvent in each picturepicture
Solute = ? Solvent = ?Solute = ? Solvent = ?
Hints to identify solute & solventHints to identify solute & solvent
• SoluteSolute: changes phase = substance have less of
• SolvenSolvent: maintains phase
= substance have most of
Aqueous SolutionsAqueous Solutions• WaterWater is
solvent
• Transition Transition metalsmetals form brightly colored solutions
Solutions occur in all 3 phases!Solutions occur in all 3 phases!
Alloys: Brass, etc.Alloys: Brass, etc.SolidSolidSolidSolid
Fillings: Hg in AgFillings: Hg in AgSolidSolidLiquidLiquidHH22 in Pd metal in Pd metalSolidSolidGasGas
Salt waterSalt waterLiquidLiquidSolid Solid
Antifreeze in radiatorAntifreeze in radiatorLiquidLiquidLiquidLiquid
Seltzer WaterSeltzer WaterLiquidLiquidGasGas
MothballsMothballsGasGasSolidSolid
Water Vapor in AirWater Vapor in AirGasGasLiquidLiquid
AirAirGasGasGasGas
ExampleSolventSolute
Gas dissolved in a solidGas dissolved in a solid
COCO22 in and out of water in and out of water
Bubbles mean it’s a mixture not a solution!Bubbles mean it’s a mixture not a solution!
SolubleSoluble
SolubleSoluble – capable of being dissolved
A substance that dissolves in another substance is solublesoluble
in that substance
Amounts that can dissolveAmounts that can dissolve
• Solubility Solubility = maximum amount of substance that will dissolve in given amount of another substance
• LIMITSLIMITS to amounts of most liquid/solid solutes that will dissolve in given solvent
• TemperatureTemperature and pressurepressure affect solubility
Factors that affect the rate of dissolvingFactors that affect the rate of dissolving
• RateRate of dissolving is of dissolving is different different from from amountamount that will dissolve! that will dissolve!
• Rate is Rate is how fasthow fast –factors influence rate of dissolving:factors influence rate of dissolving:
• TemperatureTemperature
• Stirring or Stirring or AgitationAgitation
• Surface Area of SoluteSurface Area of Solute
• Amount of soluteAmount of solute already dissolved already dissolved
DissolvingDissolving
• Dissolving is Dissolving is physical changephysical change
• All physical & chemical changes All physical & chemical changes are accompanied by changes in are accompanied by changes in energyenergy
Equations for DissolvingEquations for Dissolving
CC66HH1212OO66(s) + H(s) + H22O(l)O(l) C C66HH1212OO66(aq)(aq)
NaCl(s)+HNaCl(s)+H22O(l) O(l) Na Na+1+1(aq) + Cl(aq) + Cl-1-1(aq) (aq)
source
Covalent substances dissolve to Covalent substances dissolve to produce molecules in solutionproduce molecules in solution
Ionic substances dissolve to produce Ionic substances dissolve to produce ions in solutionions in solution
SolvationSolvation
• Interaction between solvent molecules and Interaction between solvent molecules and solute particlessolute particles– Solute particles surrounded by solvent particles in Solute particles surrounded by solvent particles in
dissolving process dissolving process
• Solute particlesSolute particles may be ions, polar molecules, may be ions, polar molecules, or nonpolar moleculesor nonpolar molecules
• Solvent moleculesSolvent molecules may be polar or nonpolar may be polar or nonpolar
HydrationHydration
Specific name for Specific name for solvent-solute solvent-solute interactioninteraction when when solvent is watersolvent is water
Hydration of Hydration of chloride ion chloride ion
Also called: Also called: molecule-ion molecule-ion interactioninteraction
Solute-solvent interactionSolute-solvent interactionmust be must be greatergreater than: than:
interaction between interaction between solute particlessolute particles
for for dissolving to occurdissolving to occur
Molecule-ion interaction
Solvation in different systems.
SolubilitySolubility
• Amount solute that will dissolve in specific Amount solute that will dissolve in specific solvent at givensolvent at given TEMPERATURE and TEMPERATURE and PRESSUREPRESSURE
• Amount can be determined experimentallyAmount can be determined experimentally
• Units: Units: grams solute per 100 grams solventgrams solute per 100 grams solvent
Solubility Curves of Selected SOLIDSSolubility Curves of Selected SOLIDS
SolubilitySolubility traces traces for for mostmost but not but not all all solidssolids have have ((+)’ve slopes;+)’ve slopes;
The hotter the The hotter the solvent, the solvent, the more solute more solute dissolvesdissolves
Solubility Curves of Selected GASESSolubility Curves of Selected GASES
SolubilitySolubility traces for traces for allall gases havegases have(–)’ve slopes(–)’ve slopes
Why do fish like cold water?Why do fish like cold water?
Why do you see Why do you see bubbles form on bubbles form on the side of the the side of the beaker as the beaker as the water warms up? water warms up? (Note: it’s not hot (Note: it’s not hot enough to boil)enough to boil)
Vocabulary InterludeVocabulary Interlude
• MiscibleMiscible: two liquids that WILL MIX together in any amounts
– Water and ethanol are miscible in all Water and ethanol are miscible in all proportionsproportions
• ImmiscibleImmiscible: Liquids that will NOT MIX– Oil and water are immiscibleOil and water are immiscible
Oil & HOil & H22O are immiscibleO are immiscible
Types of Solutions
Matter
Pure Substances Mixtures
HomogeneousMixtures =Solutions
Heterogeneous
MixturesElements Compounds
Conduct current
Nonconductor
Electricity
• What do you need to conduct What do you need to conduct electricity?electricity?
Mobile, charged particles!!!!Mobile, charged particles!!!!
Vocabulary InterludeVocabulary Interlude
• ElectrolyteElectrolyte: • substance that dissolves in water to form
solution that conducts electricity • ions in solution
• NonelectrolyteNonelectrolyte: • substance that dissolves in water to form
solution that does not conduct electricity • neutral molecules in solution
Electrolyte vs. NonelectrolyteElectrolyte vs. Nonelectrolyte
Which solution conducts a current?
Dilute vs. ConcentratedDilute vs. Concentrated
Tells relative amount of solute in solvent
• ConcentratedConcentrated
–large amounts of solute
• DiluteDilute
–small amounts of solute
Which solution is most dilute?
The most concentrated?
How do youknow?
The stronger the color, the more concentrated the solution
Which solution is more concentrated? More dilute?
What can you say about the # of solute of solute particlesparticles in pictures b and c?
It’s the same!It’s the same!
Unsaturated SolutionUnsaturated Solution
LessLess solute than maximum amount that will dissolve at given temperature and pressure
Saturated SolutionSaturated Solution
• No more solute will dissolveNo more solute will dissolve at at given temperature & pressuregiven temperature & pressure
• SolubilitySolubility = amount of solute = amount of solute required to form a saturated required to form a saturated solutionsolution
The solution is saturated when the solute The solution is saturated when the solute stops dissolvingstops dissolving
Dynamic Equilibrium = Saturated SolutionDynamic Equilibrium = Saturated Solution
Microscopic level: Rate of dissolving = Rate of dissolving = Rate of Rate of recrystallizationrecrystallization
Macroscopic level: No apparent changeNo apparent change
Supersaturated SolutionSupersaturated Solution
• Contains moremore solute than saturated solution–VERY unstable–have to be clever to make these
(need to use heat)
Testing for saturation:Testing for saturation:
Toss crystal of solute into solution and see what happens
3 possible results:3 possible results:
• Crystal dissolves:Crystal dissolves:
• Crystal sinksCrystal sinks to bottom of solution: to bottom of solution:
• Bam! Suddenly have Bam! Suddenly have lots of solid solutelots of solid solute in in beaker:beaker:
Unsaturated solution
Saturated solution
Supersaturated solution
How do terms saturated, unsaturated & How do terms saturated, unsaturated & supersaturated fit in with the solubility curves?supersaturated fit in with the solubility curves?
• Saturated solutions have maximum solute that will dissolve at given temperature – Any point on trace lines represent saturated
solutions
• All points above trace lines represent supersaturated solutions
• All points below trace lines represent unsaturated solutions
AB
CD
Characterize points Characterize points A, B, C, D with respect A, B, C, D with respect to the KNOto the KNO33 trace trace using the terms using the terms dilute & concentrated, dilute & concentrated, saturated, unsaturated, saturated, unsaturated, or supersaturatedor supersaturated
A,C = concentrated & supersaturated
B,D = dilute & unsaturated
Summary ofSummary of Dissolving Dissolving
• Occurs atOccurs at surfacesurface of solid of solid
• Involves Involves interaction betweeninteraction between solute solute andand solventsolvent
• Interaction is Interaction is called “solvation”called “solvation”– If water is solvent, interaction is called If water is solvent, interaction is called
“hydration”“hydration”
• Involves Involves changes in energychanges in energy
Solubility InformationSolubility Information
• Often presented in graphs
• Graph show number grams of substance that can dissolve in water between 0oC and 100oC
• Trace line represents saturated solution– above trace line represents supersaturated solutions– below trace line represents unsaturated solutions
Solubility GraphsSolubility Graphs
• Traces: have positive or negative slopes
• MostMost solids solids have positive slope– the hotter the water, the more solute dissolves– The colder the water, the less solute dissolves
• AllAll gases gases have negative slope – the hotter the water, the less gas dissolves– The colder the water, the more gas dissolves