itt chng ch 12 properties of solutions

7/29/2019 ITT Chng Ch 12 Properties of Solutions

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Physical Properties of Solutions


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12.1

A solutionis a homogenous mixture of 2 or

more substances

The soluteis(are) the substance(s) present in thesmaller amount(s)

The solventis the substance present in the larger

amount


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A saturated solutioncontains the maximum amount of a

solute that will dissole in a gien solent at a specific

temperature.

An unsaturated solutioncontains less solute than thesolent has the capacity to dissole at a specific

temperature.

A supersaturated solutioncontains more solute than ispresent in a saturated solution at a specific temperature.

Sodium acetate crystals rapidly form when a seed crystal is

added to a supersaturated solution of sodium acetate.

12.1


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12.2

Three types of interactions in the solution process!" solent#solent interaction" solute#solute interaction" solent#soluteinteraction

$soln% $1& $2& $'


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like dissolves like

Two substances with similar intermolecularforces are li*ely

to be soluble in each other.

" non#polar molecules are soluble in non#polar solents

++l,in +-$-

" polar molecules are soluble in polar solents

+2

$

/$ in $2

/

" ionic compounds are more soluble in polar solents

0a+l in $2/ or 0$'(l)

12.2


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+oncentration nits

The concentrationof a solution is the amount of solute

present in a gien uantity of solent or solution.

Percent by Mass

3 by mass % x 1443

mass of solute

mass of solute & mass of solent

% x 1443mass of solute

mass of solution

12.'

Mole Fraction(X)

XA%moles of A

sum of moles of all components


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+oncentration nits +ontinued

M %moles of solute

liters of solution

Molarity(M)

Molality(m)

m % moles of solutemass of solent (*g)

12.'


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5hat is the molality of a .6- Methanol (+2$/$)

solution whose density is 4.728 g9m:;


M % moles of solute

liters of solution

Assume 1 : of solution!

.6- moles ethanol % 284 g ethanol728 g of solution (1444 m: x 4.728 g9m:)

mass of solent % mass of solution < mass of solute

% 728 g < 284 g % -8 g % 4.-8 *g

m %moles of solute

mass of solent (*g)%

.6- moles +2$/$

4.-8 *g solent% 6.72 m

12.'


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Temperature and Solubility

Solid solubility and temperature

solubility increases withincreasing temperature

solubility decreases with

increasing temperature

12.,


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Fractional crystallizationis the separation of a mixture of

substances into pure components on the basis of their differing

solubilities.

Suppose you hae 74 g =0/'

contaminated with 14 g 0a+l.

>ractional crystalli?ation!

1. @issole sample in 144 m: ofwater at -44+

2. +ool solution to 44+

'. All 0a+l will stay in solution

(s % ',.2g9144g),. 86 g of PB =0/'will

precipitate (s % 12 g9144g).

74 g < 12 g % 86 g

12.,


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Temperature and Solubility

/2gas solubility and temperature

solubility usuallydecreases with

increasing temperature

12.,


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Pressure and Solubility of Cases

12.

The solubility of a gas in a liuid is proportional to the

pressure of the gas oer the solution (Henrys law).

c% kP

cis the concentration (M) of the dissoled gas

Pis the pressure of the gas oer the solution

kis a constant for each gas (mol9:"atm) that

depends only on temperature

low P

low c

high P

high c


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Chemistry In Action:The =iller :a*e

Lake Nyos, West Africa

8!"8#

C$!Clo%d &eleased

"'(( Cas%alties

)ri**er+

" earth%ake

" landslide

" stron* Winds


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+olligatie Properties of 0onelectrolyte Solutions

Colligative propertiesare properties that depend only on the

n%mberof solute particles in solution and not on the nat%reofthe solute particles.

-a.or/Press%re Lo0erin*

Raoults law

Df the solution contains only one solute!

X1% 1


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PA%XA P A4

PE%XE P E4

PT% PA& PE

PT%XA P A4 +XE P E

4

Ddeal Solution

12.-


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PTis greater than

predicted by aoultsFs law

PTis less than

predicted by aoultsFs law

>orce

A#E

>orce

A#A

>orce

E#EG H

>orce

A#E

>orce

A#A

>orce

E#EI H

12.-


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Fractional 1istillation A..arat%s

12.-


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2oilin*/Point 3levation

Tb% Tb< T b4

TbI T b4

TbI 4

T bis the boiling point of

the pure solent

4

T bis the boiling point of

the solution

Tb% Kbm

mis the molality of the solution

Kbis the molal boiling#point

eleation constant (4+9m)

for a ien solent12.-


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Free4in*/Point 1e.ression

Tf% T f < Tf4

T fI Tf4

TfI 4

T f is the free?ing point of

the pure solent

4

T f is the free?ing point of

the solution

Tf% Kfm

mis the molality of the solution

Kfis the molal free?ing#point

depression constant (4+9m)

for a gien solent 12.-


20/30 12.-


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5hat is the free?ing point of a solution containing ,86 g

of ethylene glycol (antifree?e) in '242 g of water; The

molar mass of ethylene glycol is -2.41 g.

Tf% Kfm


% 2.,1 m%'.242 *g solent

,86 g x1 mol

-2.41 g

Kfwater % 1.6-4+9m

Tf% Kfm % 1.6-4+9mx 2.,1 m% ,.,6 4+

Tf% T f < Tf4

Tf% T f < Tf4 % 4.44 4+ < ,.,6 4+ % #,.,6 4+

12.-


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$smotic Press%re 56

12.-

Osmosisis the selectie passage of solent molecules through a porous

membrane from a dilute solution to a more concentrated one.

A semipermeable membraneallows the passage of solent molecules butbloc*s the passage of solute molecules.

Osmotic pressure ()is the pressure reuired to stop osmosis.

dilutemore

concentrated


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$igh

P

:ow

P

$smotic Press%re 56

% MRT

M is the molarity of the solution

Ris the gas constant

Tis the temperature (in =) 12.-


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A cell in an:

12.-

isotonic

solution

ypotonic

solution

ypertonic

solution


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+olligatie Properties of 0onelectrolyte Solutions

Colligative propertiesare properties that depend only on the

n%mberof solute particles in solution and not on the nat%reof

the solute particles.

12.-

-a.or/Press%re Lo0erin* P1%X1 P 14

2oilin*/Point 3levation Tb% Kbm

Free4in*/Point 1e.ression Tf% Kfm

$smotic Press%re 56 % MRT


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+olligatie Properties of Blectrolyte Solutions

12.8

4.1 m0a+l solution 4.1 m0a&ions H 4.1 m+l#ions

Colligative propertiesare properties that depend only on then%mberof solute particles in solution and not on the nat%reof

the solute particles.

4.1 m0a+l solution 4.2 mions in solution

vant Ho!! !actor (i)%actual number of particles in soln after dissociation

number of formula units initially dissoled in soln

nonelectrolytes

0a+l

+a+l2

ishould be

1

2

'


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2oilin*/Point 3levation Tb% iKbm

Free4in*/Point 1e.ression Tf% i Kfm

$smotic Press%re 56 % iMRT

+olligatie Properties of Blectrolyte Solutions

12.8


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A colloidis a dispersion of particles of one substance

throughout a dispersing medium of another substance.

+olloid ersus solution" collodial particles are much larger than solute molecules

" collodial suspension is not as homogeneous as a solution

12.6


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The +leansing Action of Soap

12.6


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Chemistry In Action:

@esalination

itt chng ch 12 properties of solutions

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