LECTURE №4 DISPERSE SYSTEMS. TRUE SOLUTION 21.0 2.201 7

and colloids.

2) Understand, compare, and contrast the terms homogeneous mixture

and heterogeneous mixture. For a homogeneous mixture, explain the difference between solute(s) and solvent.

3) Predict the effect of temperature and pressure on the solubility of gases in water and the effect of temperature on the solubility of solids in water.

4) Be able to use the Solubility Rules Table to determine if an ionic compound will significantly dissolve in water.

5) Be able to calculate the concentration of a solution using various concentration units of measurements. (%, parts per thousand, molarity, molality, normality and titer)

form of very small particles (in the form of droplets,

dust, gas bubbles) is uniformly distributed in a medium (volume) of the other.

Disperse System composed of:
Dispersed phase – substance that is distributed
Dispersion medium – the continuous Phase or vehicle (acts as a solvent)

solution, homogeneous system
Sol – microheterogeneous system
Molecular
Mixed (molecular-ionic)
Ionic

studied for the first time by Tyndall. The illuminated path

of the beam is called Tyndall cone.

When light passes through a sol, its path becomes visible because of scattering of light by particles. It is called Tyndall effect.

= 10-7 – 10-9 cm
SUSPENSIONS
D> 10-7 cm

in water
compound
a heterogeneous mixture
a homogeneous mixture

or more substances in a single phase

SOLUTE – the part

of a solution that is being dissolved (usually the lesser amount)

SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)

SOLUTE
+ = SOLUTION
SOLVENT

is the substance that is dissolved. What is the name

of this part of a solution?

solvent

vehicle

solution

solute

–electrolytes, e.g. organic substances
Ionic solution:
soluble electrolytes solution – salts,

bases, acids

Mixed (molecular-ionic) solution

solvent particles to form a solution
SOLUTE
Soluble – a substance that

dissolves in a solvent

Insoluble – a substance that does not dissolve in a solvent

grams, that can be dissolved in 100 g of water

at a specific temperature and pressure.
UNSATURATED – a solution that contains less dissolved solute
SATURATED – a solution that contains the maximum amount of dissolved solute
SUPERSATURATED – a solution that contains more dissolved solute than a saturated solution at the same temperature (as result solute will usually precipitate out of solution)

solute dispersed in the solvent

The Concentrated is a solution in

which large amount of solute is dissolved in the solvent

from a more concentrated solution.

(both H-bonded polar liquids).
Immiscible liquids form distinct separate phases, e.g.

gasoline (non-polar) and water (polar).

colorless CCl4

green NiCl2(aq)

colorless C7H16

Solute-Solvent Interactions

after mixing and settling

tend to dissolve in polar solvents.
Non-polar substances tend to dissolve

in non-polar solvents.

2) Temperature – solubility usually increases as T increases

3) Pressure – for gas solution solubility increases with the P

liquid solvents increases with increasing temperature.
The solubility of gas solutes

in liquid solvents decreases with increasing temperature.

dissolve.
The solubility of liquids and solids does not change appreciably

with pressure.
But, the solubility of a gas in a liquid is directly proportional to its pressure.

a gas in a liquid is proportional to the partial

pressure of the gas over the solution (Henry’s law).

c = k•P

c is the concentration (mol) of the dissolved gas
P is the partial pressure of the gas over the solution
k is a constant (mol/L•atm) that depends only
on temperature

substance dissolving in an aqueous solution. It represents the level

at which a solute dissolves in solution:  

given amount of solvent is represented by the …
Volume of

the solution

Mass of the solute

Mass of the solution

Concentration of the solute

present in a given quantity of solvent or solution.
There are

many different units for this purpose, including:
Percent by weight or volume,
Molarity,
Normality,
Molality,
Titer.

Concentration Units

solute divided by the mass of the solution, multiplied by

100 (%):



2) Molarity is the number of moles of solute per liter of solution (mol/l):

a solute per 1 liter of solution (mol*eq/l):



4) Molality

is the number of moles of solute per 1 kilogram of solvent (mol/kg):

per 1 milliliter of solution (g/ml):