SolutionsSolutions

•Are homogeneous mixturesAre homogeneous mixtures

•A physical combination of A physical combination of two or more substances, that two or more substances, that

appear to be only oneappear to be only one

• The parts of a solution are referred to The parts of a solution are referred to as the solute and the solvent.as the solute and the solvent.

• The solute is the part that The solute is the part that disappears disappears into the solvent. (dissolves into the into the solvent. (dissolves into the solvent)solvent)

• The solvent is the part that does not The solvent is the part that does not disappear.disappear.

Types of SolutionsTypes of Solutions

• If you combine the three states of If you combine the three states of matter in every possible way, you matter in every possible way, you get 9 types.get 9 types.

Type of solution example solute solventType of solution example solute solvent

Solid in liquid Solid in liquid sea water sea water salt salt water water Tincture betadiene iodine alcoholTincture betadiene iodine alcohol Solid in a solid alloys ( Brass) zinc copperSolid in a solid alloys ( Brass) zinc copper

Solid in gas smoke fine wood airSolid in gas smoke fine wood air or Real fine dust or Real fine dust

Gas in liquidGas in liquid soda CO soda CO22 water water Or blood oxygen blood serum Or blood oxygen blood serum

Gas in gasGas in gas air air oxygen nitrogen oxygen nitrogen

Gas in solid air freshener odors baking sodaGas in solid air freshener odors baking soda Gas mask tear gas charcoal Gas mask tear gas charcoal

Liquid in liquid vodka alcohol water Liquid in liquid vodka alcohol water

Liquid in gas humid air water air Liquid in gas humid air water air Liquid in solid amalgam mercury silverLiquid in solid amalgam mercury silver ( Tooth filling )( Tooth filling )

• Aqueous solutions are ones in which Aqueous solutions are ones in which water is the solvent. water is the solvent.

• Tincture is a solution, in which Tincture is a solution, in which alcohol is the solventalcohol is the solvent

• Miscible – liquids that are mutually Miscible – liquids that are mutually soluble in each other. Alcohol and soluble in each other. Alcohol and water water

• Immiscible – liquids that do not Immiscible – liquids that do not dissolve in each other. Oil and dissolve in each other. Oil and waterwater

SolubilitySolubility

• How much of a solute that can dissolve How much of a solute that can dissolve in a given amount of solvent.in a given amount of solvent.

• Normally expressed as grams of solute Normally expressed as grams of solute per 100 grams of solvent. But can be per 100 grams of solvent. But can be othersothers

• a Saturated solution, Contains the a Saturated solution, Contains the maximum amount of solute possible.maximum amount of solute possible.

• Unsaturated does notUnsaturated does not

• Supersaturated contains more solute Supersaturated contains more solute than a normal saturated solution. than a normal saturated solution. They are hard to make and very They are hard to make and very unstable. The extra solute unstable. The extra solute precipitates out very easily precipitates out very easily

The Dissolving The Dissolving MechanismMechanism• Three things have to happen in order for Three things have to happen in order for

stuff to dissolve. stuff to dissolve. • 1 The solvent must separate to allow the 1 The solvent must separate to allow the

solute to enter. ( water moves aside when solute to enter. ( water moves aside when you jump in) that requires work, energy.you jump in) that requires work, energy.

• 2 The solute must break apart. 2 The solute must break apart. (dissociation) That also requires energy. (dissociation) That also requires energy.

• 3 The solute and solvent must attract each 3 The solute and solvent must attract each other. That releases energyother. That releases energy

• The combination of those 3 energies The combination of those 3 energies determines if the dissolving mechanism determines if the dissolving mechanism is endothermic or exothermic.is endothermic or exothermic.

• Endothermic heat must be added to get Endothermic heat must be added to get it to dissolve.it to dissolve.

• Exothermic will give off heat as it Exothermic will give off heat as it dissolvesdissolves

• Heat of SolutionHeat of Solution• demos would be good.demos would be good.

Factors affecting Factors affecting SolubilitySolubility

1 Nature of the solute and solvent1 Nature of the solute and solvent

are they polar or nonpolar molecules? are they polar or nonpolar molecules?

polarity is back , look over your old polarity is back , look over your old

notes.notes.

likes dissolve likes likes dissolve likes

polars dissolve other polars, polars dissolve other polars,

nonpolar dissolve nonpolarnonpolar dissolve nonpolar

Solvation ( Hydration)Solvation ( Hydration)

2 Temperature – an increase in temp 2 Temperature – an increase in temp will increase the solubility of will increase the solubility of substances that have endothermic substances that have endothermic dissolving mechanism.dissolving mechanism.

and decrease the solubility of the and decrease the solubility of the

exothermic ones. exothermic ones.

increase in temp increases the increase in temp increases the solubility of solubility of mostmost solids in a liquid solids in a liquid

you can dissolve more sugar in hot you can dissolve more sugar in hot tea than cold tea.tea than cold tea.

• You have to be able to read this type of graph and apply the You have to be able to read this type of graph and apply the information.information.

An increase in temp decrease the An increase in temp decrease the solubility of most gases in a liquid. solubility of most gases in a liquid.

That why trout die in warm water, That why trout die in warm water, there is not enough oxygen in it. there is not enough oxygen in it.

( Explain in terms of gases dissolving and leaving solution )

3 Pressure3 Pressure

Pressure only affects solutions in which Pressure only affects solutions in which the solute is a gas. the solute is a gas.

gas in liquid is most common, more gas in liquid is most common, more pressure forces more gas into the pressure forces more gas into the solutionsolution

That is what causes scuba divers to get That is what causes scuba divers to get the bends if they come up to fast.the bends if they come up to fast.

also big fish deep water?also big fish deep water?

More pressure on the top surface of the liquid causes more collisions on the top surface, which means more gas goes in than comes out.

Factors that affect the Factors that affect the RateRate of of Solubility Solubility • TemperatureTemperature

• Surface areaSurface area

• StirringStirring

• How and why?How and why?

• demosdemos

Expressing solution Expressing solution ConcectrationConcectration

• MolarityMolarity

• Molality Molality

• Percent by massPercent by mass

• NormalityNormality

• Parts per millionParts per million

MolarityMolarity

Molarity = Molarity = moles of solute moles of solute liter of solutionliter of solution

( Demo use of volumetric flask and the difference between the two.)

Molality = moles of solute

liters of solvent

Pages 483-484

Percent by massPercent by mass

Percent by mass = Percent by mass = mass of solutemass of solute X 100 X 100 mass of solutionmass of solution

Or mass of solute / mass of solution times 100Or mass of solute / mass of solution times 100

Parts per million is the same as above except you multiply by 1,000,000

Normality Normality

Normality = Normality = gram equivalentsgram equivalents

liter of solutionliter of solution

( Explain what a gram equivalent is )

Colligative Properties of Colligative Properties of solution solution

colligative properties are properties of colligative properties are properties of a solvent that are affected by the a solvent that are affected by the presence of a solute.presence of a solute.

The properties are affected by the The properties are affected by the numbernumber of particles of particles not their not their identityidentity

We will talk about three colligative We will talk about three colligative properties.properties.

Boiling pointBoiling point

Freezing point Freezing point

Vapor pressureVapor pressure

The presence of salt in water, will raise the The presence of salt in water, will raise the boiling point and lower the freezing point. boiling point and lower the freezing point.

It extends the liquid range in both directions before there is a phase change

You may ask, how much ?

For boiling - .51°C per mole of solute per liter of solvent

For freezing – 1.86° C per mole of solute per liter of solvent

This is why we put salt on the roads This is why we put salt on the roads and anti-freeze in our cars. and anti-freeze in our cars.

How much do we need?

There is math for that!

∆ ∆ TTbb = K = Kbbm m

∆ ∆ (delta ) T(delta ) Tbb is the change in boiling temp, is the change in boiling temp,

KKbb is the molal boiling point constant is the molal boiling point constant

.51 .51 °°C per mole/liter, and m is the molality of C per mole/liter, and m is the molality of the solution.the solution.

∆ ∆ TTff = K = Kffm m

∆ ∆ (delta ) T(delta ) Tff is the change in freezing is the change in freezing

temp,temp,

KKff is the molal freezing point constant is the molal freezing point constant

1.861.86°°C per mole/liter, and m is the molality C per mole/liter, and m is the molality of the solution.of the solution.

Every solvent has its own Kb and Kf value.

“ “That’s all folks”That’s all folks”