SOLUTIONS –

• homogeneous dispersion of two or more substances in an ionic or molecular scale

Na+

O H

H

Cl- H O

H

CHO

CH OH

CH2OH

O H

H

Very small particles, too small to be seenBy the unaided eye

Kinds of Mixture Particle Size

suspension

colloid

solution

10-4 cm. in diameter

10-5 – 10-6 cm. in diameter

10-7 cm. in diameter

Always suspended in the medium (too small to be pulled down by gravity)Shows Tyndall Effect : reflect light to produce a visible beam of light

Always suspended in the medium ( too small to be pulled down by gravity)

Settles upon standing

Kinds of Solutions

Solid state Alloys ( Coin, brass)

Liquid state Sea water, alcohol in waterDissolved Oxygen (DO)

Gaseous state Air

Parts of a Solution

solution

solute

solvent

Dissolved substance

Dissolving medium

is

is

Parts of a solution

Physical state amount

Solute Dissolved substance

Solid, gas Less

Solvent Dissolving medium

liquid more

Nature of Dissolving Process:

Na+

Na+

Na+

Na+

Cl-

Cl-

Cl-

Cl-

H OH Cl

-H2O

H2O

H2O

H2O

solvated iondissolving rate

crystallizing rate

salt

Nature of the Dissolving Process

Na+1

Na+1 Na+1

Cl-1Na+1

Cl-1

Cl-1Cl-1

Cl-1 Na+1

H2O

H2O

H2O

H2O

Dissolving rate

Crystallizing rate

saltSolvated ion

Nature of Dissolving Process:

• The nature of the dissolving process is• a 2 way process1. Process of dissolution2. Process of crystallization

Which, at one point in time the 2 processes will attain equilibrium

• At equilibrium

• Rate of dissolution == rate of crystallization

• Solution is called saturated solution

• Concentration of the solution is constant

• corresponds to the solubility of the solute in question .•

Solubility –

• maximum amount of solute that will be dissolved by a given amount of solvent producing a stable system, under a specified temperature

Factors affecting SolubilityNature of solute and solvent :

• Like Dissolves Like

IMFAsolute &solvent

IMFAsolute

IMFAsolvent

Temperature

Heat of solution

Solid in liquid

Gas in liquid

T increases solubility increases

Endothermic

T increases solubility decreases

exothermic

exothermicT increases solubility decreases

Pressure

• Pressure –has little or no effect on the solubility of solid in liquid, liquid in liquid

• Gas in liquid : Pressure increases, solubility increases

When can a gas become soluble in water ?

gas

liquid

For the gas to become soluble in the liquid , it must comeinto contact with the liquid: IMFA forming ( exothermic heatflow )

Applied Pressure: Pressure increases, solubility of gas in water increases

And this will be effectedby applying pressure to the gas so that IMFA is formed between the gas and water.

A process which involvesIMFA forming results for heatTo flow out to the sorrounding.

Factors affecting Rate of Dissolution

1. Temperature : As temperature increases, rate of dissolving increases.

2. Stirring increases rate of dissolving3. Surface area – As surface area increases, rate

of dissolving increases

Concentration = is the amount of solute present in a given amount of solvent producing a solution

Described

qualitatively quantitatively

dilute concentrated

saturated

unsaturated supersaturated

% Molarity (M)

Normality (N)

Molality (m) Mole fraction (X)

1. Dilute- contains a relatively low amount of solute2. Concentrated – contains a relatively high amount of solute 3. Saturated – contains the maximum amount of solute that

can be dissolved by a measured amount of solvent (solubility equivalent )

4. Unsaturated – one which contains solute concentration lower than the concentration in the saturated solution.

5. Supersaturated – one which contain solute concentration higher than the concentration in the saturated Solution.

Dilute concentrated

46.5 g NaAc/100 g H2O25 C

solubility

80 g NaAC/100 g H20 50 C

all 80 g solutedissolves cool to

25 C

all 80 g NaAc is inwater as a solutionindefinitely

called

supersaturatedsolution

which canbe destroyed by

seeding agitation

Saturated supersaturated

If amount of NaAc is < 46.5 g in 100 g H2OAt 25 oC

Unsaturated solution

Saturated solutionWith undissolvedsolute

A B C

At the start of Dissolving

Solute amount in Solvent is zero

During dissolving

Solute amount in solvent Has increased, but still lessThan the dissolving rate

After dissolving

Solute amount in solvent Has increased so that dissolvingRate is equal to the crystallizing rate

At what point during the dissolving rate is the saturated solution ?C

Not a solution Unsaturated solution Saturated solution

QUANTITATIVE METHODS OF EXPRESSING CONCENTRATION OF SOLUTION

SOLUTION

SOLUTE SOLVENT/WATER

%

Molarity

Normality

molality

Mole fraction

PerCent = Part Quantity/Total Quantity X 100

1. Percent by mass = grams ofsolute/grams of solution X 100

2. Percent by volume = volume of solute/volume of solution X 100

3. Percent by mass-volume = grams of solute/volume of solution X 100

A 0.50 liter bottle of wine contains 60 ml ethanol. What is the % v/v ethanol in the solution ?

SOLUTION

SOLUTE SOLVENT

0.50 liter

60 ml

volume solute % = ------------------- X 100 volume solution

How many grams of KCl are required to prepare 250 grams of an aqueous solution that is 10.0 % KCl by mass

SOLUTION

SOLUTE SOLVENT

?

250 grams

means

10 g KCl = 100 g solution

Conversion factor

Molarity (M)

SOLUTION

SOLUTE SOLVENT/WATER

MOLE

Wt./MW

LITER

OR

What is the M of a 10 % HCl solution of a density of 1.2 g /ml

SOLUTION

SOLUTE SOLVENT

10 g HCl = 100 g solution

10g HCl = 100 g soluton

means

M = wt/mwt/liter

NORMALITY (N)

SOLUTION

SOLUTE SOLVENT/WATERNumber of equivalents ( (wt/MW ) X F )

Number of milliequivalents( (wt/MW) X F X 1000)

LITER

milliliter

Mole fraction (X)

SOLUTION

SOLUTE SOLVENT/WATER

mole Mole Add to

Mole total

Mole solute/mole total

Molality (m)

SOLUTION

SOLUTE SOLVENT/WATER

MOLE

Wt./MW

OR KG

Calculate the molality of a solution of 2.34 g acetic acid, HC2H3O2 in 35.0 g water

SOLUTION

SOLUTE SOLVENT

2.34 g

HC2H3O2

35.0 g

MWT = 60.0 g/mole wt/ MWT solute m = ------------------- Kg solvent

DILUTION

• = process of adding water to a solution of known concentration to obtain a new solution of different concentration

6M HCl300 mL.

+ 300 ml water3M HCl600 mL

solute solute

add water

What happens to the amount of solute upon dilution ?

1.8 moles 1.8 moles

6M HCl300 mL.

+ 300 ml water3M HCl600 mL

IN DILUTION

• :• Amount of solute in original solution = amount of solute in the prepared solution•

Calculate the M of

55.0 g NaCl in 125 ml of solution

SOLUTIONso

SOLUTE SOLVENT

55.0 g 125 ml

M = wt/mwt/liter

Theory Acid Base

ArrheniusOne which contains a hydrogen which will be yielded as a H+1 in water

One which contains a hydroxide which will be yielded as OH-! In water

Bronstead Lowry Proton donor Proton acceptor

Lewis E’ pair acceptor E’ pair donor

H Cl H+1

+ Cl

It has H +1: has a potential to donate

Proton donor

Bronsted acid H+1

E pair acceptor

Lewis acid

Arrhenius acid

+ 2e' H

Na OH OH-1

Na+1

+

it has OH w/c is negative; potential proton acceptor

Bronsted baseOH

-1Na

+1+

Has several e’ pairs; potential e’ pair donor

Lewis base

Arrhenius base

HCl H2O H+ Cl

-

+

AcidConjugate base

What had become of the acid after donating a proton

NH3 NH4+

H2O

OH-

BASE CONJUGATE ACID

What had become of the base after donating2 electrons

HCl H2O H+ Cl

-

+

acid Conjugate base

base Conjugate acid

A strong acid has a weak conjugate base

SAWeak

SB

At equilibrium weak are favored

solute Solvent (water)

solution

electrolytes

Strong :HCl H

+Cl

-+

NaOH Na+

OH-+

Weak

HC2H3O2 H+ C2H3O2

-+

Mg( OH) 2 Mg+2

2 OH-

+

Aside as being a solvent , something important is happening to water

Acid, base, salt

H2O dissociates (into ions) to an extremely small but very important degree.

Kw = 1 X 10 -14 ( 0.00000000000001)

T= 250 C

H2O H+

OH-

+

Arithmetically of the value

1x10 -7 M 1x10 -7 M

WATER IS A NON ELECTROLYTE

Ion product constant :

Kw = (H+) (OH-)

Called

aciditybasicity

neutral

solution

• solute • Solvent (water)electrolyte Non electrolyte

HCl H+1Cl +

NaOH OH-Na

+1+

acid

base

HOHH+OH

-

+

Interplay of these ions is

ACIDITY AND OR BASICITY

Possible interplays are

H+ OH

-

H+ OH

-

H+ OH

-

<

>

=

Acidic

basic

neutral

When an acid is added to water , the H+ concentration of the resulting solution is determined solely by the acid

base OH-

base

HCl Cl-

H+

0.01 M

H2O H+ OH

-

H+

solution

=

0.01

0.01

NaOH Na+

OH-

+

0.02 M

H2O H+

OH-

+

OH-

solution

=

0.02 M

0.02 M

Small amount

acidic

Small amount

basic

Colligative Properties- dependent only on the ratio of the number of solute particle to the number of solvent particles and not on

the nature of the solute.

• Vapor pressure lowering• Boiling point elevation• Freezinf point Depression• Osmotic Pressure

Does not matter wether solute is an acid or base or salt

Vapor pressure

P air

Temperature : Boiling point

solvent

Vapor pressure

P air

Solute occupies some areas of the liquid and interfers with the evaporation

less

Vapor pressure

P air

TBoiling point Elevation

more