SolutionsSolutions

Test on Friday March 4Test on Friday March 4

What is a What is a solutionsolution??

A A homogeneous mixturehomogeneous mixture Composed of a Composed of a solute solute dissolved in a dissolved in a

solventsolvent Solute

Solvent

How is a solution formed?How is a solution formed?

Through the process ofThrough the process of Solute particlesSolute particles separate from each other and separate from each other and

mix with the mix with the solvent solvent particlesparticles

Solvent particlesSolvent particles surround the surround the solute solute particlesparticles and pull and pull them away from other them away from other solute particles solute particles

solvation

Solute and SolventSolute and Solvent

SolventSolvent Does the Does the dissolvingdissolving GreaterGreater quantity (usually) quantity (usually)

SoluteSolute What is dissolvedWhat is dissolved LesserLesser quantity (usually) quantity (usually)

Like dissolves likeLike dissolves like Baking soda will dissolve in water, but not Baking soda will dissolve in water, but not

in oil…..why?in oil…..why? ““Like dissolves like” refers to the Like dissolves like” refers to the bonding bonding

and polarityand polarity of the particles in the of the particles in the solute solute and solventand solvent

Polar means a substance Polar means a substance has a has a positive positive and a and a negativenegative end end

Ionic Ionic compoundscompounds

Ionic compounds in solutionIonic compounds in solution

Cl- Na+ Cl- Na+

Na+Cl- Cl-

SolubilitySolubility Only a certain amount of solute can dissolve in a Only a certain amount of solute can dissolve in a

solvent under a certain set of conditionssolvent under a certain set of conditions When too much solute is added to a solution at When too much solute is added to a solution at

that temperature, the excess solute will that temperature, the excess solute will crystallize crystallize

and fall out of solutionand fall out of solution SolubilitySolubility is the is the maximummaximum

amount of a soluteamount of a solute that that

dissolves in a solvent at dissolves in a solvent at

a a given temperaturegiven temperature

SaturationSaturation

A A saturatedsaturated solution solution contains the contains the maximum amountmaximum amount of of

dissolved solute dissolved solute for a given for a given amount of solventamount of solvent at a at a specificspecific temperaturetemperature and and pressurepressure

SupersaturationSupersaturation A supersaturated solution A supersaturated solution

contains contains moremore dissolved solute than a dissolved solute than a saturated solution saturated solution

at the at the samesame temperature. temperature.

Solubility CurvesSolubility Curves

Shows how much solute will dissolve in 100 g of water at a certain temperature

The line represents the saturated amount of solute

Underneath the line represents an unsaturated amount

Above the line represents a supersaturated amount

• Which substance is most soluble at 40°C?• How many grams of NH4Cl will dissolve at 50°C?

• What two substances have the same solubility at 24°C?

• If you place 70 grams of KBr into 100g of water at 60°C, whattype of solution have you made?

• How many grams of NaNO3 will dissolve in 300.0g of water at 10.0°C?

NaNONaNO33

~ 50 ~ 50 gramsgrams

YbYb22(SO(SO44))

33

KNO33unsaturatedunsaturated

~ 240 ~ 240 gramsgrams

(80 x 3)(80 x 3)

Increasing Solubility - SolidsIncreasing Solubility - Solids

Increase the Increase the temperaturetemperature Why? Increases the amount of Why? Increases the amount of solute-solute-

solvent collisionssolvent collisions and increases and increases speed and speed and energyenergy of particles of particles

AgitateAgitate the solution (stir) the solution (stir) Why? Brings more Why? Brings more

solvent particlessolvent particles closer to closer to the the solutesolute

Decrease the particle sizeDecrease the particle size IncreasesIncreases the the surface areasurface area

of the solute, making it of the solute, making it easier for solvent particles to easier for solvent particles to surround the solute surround the solute

Increasing Solubility – Increasing Solubility – GasesGases

Decrease the Decrease the temperaturetemperature Increase the Increase the pressurepressure If you increase the pressure, If you increase the pressure,

think of pressing the gas think of pressing the gas particles into the liquid.particles into the liquid.

Increasing pressure always Increasing pressure always increases the amount of increases the amount of gasgas that can be that can be dissolveddissolved in a liquid.in a liquid.

Rate of SolvationRate of Solvation

Greater solubility = Faster solvationGreater solubility = Faster solvation The same factors that increase The same factors that increase

solubility, increase the rate of solubility, increase the rate of solvationsolvation

ConcentrationConcentration

The larger the The larger the ratioratio of solute to of solute to solvent becomes, the more solvent becomes, the more concentratedconcentrated the solution is. the solution is.

ConcentratedConcentrated – large ratio of solute – large ratio of solute to solventto solvent

DiluteDilute – small ratio of solute to – small ratio of solute to solventsolvent

Rates of ReactionRates of Reaction

Concentration affects the rate of Concentration affects the rate of reactionreaction

ConcentratedConcentrated solutions react solutions react fasterfaster than than dilutedilute solutions solutions

MolarityMolarity

Most commonly used in chemistryMost commonly used in chemistry Abbreviated as Abbreviated as MM MolesMoles of solute in per of solute in per literliter of solution of solution

moles of soluteLiters of solution

M =

ElectrolytesElectrolytes Electrolyte – ionic compound whose Electrolyte – ionic compound whose

aqueous solution conducts an electric aqueous solution conducts an electric currentcurrent

– – electrolyteelectrolyte – – non-electrolytenon-electrolyte

NaClNaCl

SugarSugar

How many moles of ions are produced by dissolving 1 mole of NaCl in water?

Colligative PropertiesColligative Properties

Colligative - depending on the Colligative - depending on the collectioncollection

Properties dependent on Properties dependent on concentrationconcentration, number of particles , number of particles presentpresent

Boiling Point ElevationBoiling Point Elevation When vapor pressure equals When vapor pressure equals

atmospheric pressure, water boilsatmospheric pressure, water boils More particles = More particles = lowerlower vapor pressure vapor pressure Lower vapor pressure = Lower vapor pressure = higherhigher boiling boiling

pointpoint More particles = More particles = higherhigher boiling point boiling point

Which raises boiling point more, 1 mole of NaCl in water, or 1 mole of sugar in water?

Freezing Point DepressionFreezing Point Depression Solute particles Solute particles

interfere with interfere with attraction between attraction between solvent particlessolvent particles

MoreMore particles = particles = lowerlower freezing point freezing point

OsmosisOsmosis Osmosis – diffusion of Osmosis – diffusion of solventsolvent across a across a

semi-permeable barriersemi-permeable barrier Solvent goes from:Solvent goes from:

Area of Area of moremore solvent solvent → Area of → Area of lessless solventsolvent

OsmosisOsmosisSemi-permeable

barrierPure Solvent

Solution

Osmosis and ConcentrationOsmosis and Concentration Higher concentration = Higher concentration = moremore osmotic osmotic

pressurepressure

Osmosis and you

Colligative Properties Colligative Properties ReviewReviewAtmosphere

Vapor Pressure

Miscible and Immiscible

Substances that are miscible will dissolve in each other. Example: alchohol and water

Substances that are immiscible will mix but immediately separate. Example: oil and vinegar