3. What Is a Solution?
• is a type of homogeneous mixture
that is made up of two or more
substances.
• A homogeneous mixture is a type
of mixture with a uniform
composition.
4. Let's make use of our salt water example to talk about
the two main parts of a solution. These are:
Solute: this is the substance that makes up the minority
of the solution, or this is the part that is dissolved.
Example, the salt water, the solute is the salt.
Solvent: this is the substance that makes up the majority
of the solution. This is the part where the solute is
dissolved. Example, the salt water, the solvent is water.
5. TYPES OF SOLUTIONS
On the basis of physical states of solute and solvents
Gaseous Solutions: gases can spontaneously mix in any
proportion.
Solid Solutions: they are generally called alloys, where
two or more metals are present. Mercury alloys are called
amalgams, and they can be liquid or solid.
Liquid Solutions: liquid solutions are the most common
and they can be obtained by dissolution of a gaseous,
liquid or solid solute.
6. TYPES OF SOLUTIONS
On the basis of dissolution of solute in solvent
A saturated solution contains the maximum amount of a
solute that will dissolve in a given solvent at a specific
temperature.
An unsaturated solution contains less solute than the
solvent has the capacity to dissolve at a specific
temperature.
A supersaturated solution contains more solute than is
present in a saturated solution at a specific temperature.
7.
8. Energies of Solution Formation
• "Like dissolves like"
Step 1: Seperating the solution into individual components
the solute (expanding the solute).
Step 2: Overcoming intermolecular forces in the solvent to
make room for the solute (expanding the solute)
Step 3: Allowing the solute and solvent to interact to form
the solution
• Enthalpy of hydration is step 1 and step 2 combined into 1
step
11. Concentration Units
The concentration of a solution is the
amount of solute present in a given
quantity of solvent or solution.
12. a.) Percent by Mass
% by mass =
mass of solute
mass of solute + mass of solvent
x 100%
=
mass of solute
solute mass of solution
x 100%
Percent by Volume
% by volume =
volume of solute
volume of solution
x 100%
13. b.) Mole Fraction (X)
𝑋𝐴=
moles of A
sum of moles of all components
c.) Molarity (M)
M =
moles of solute
liters of solution
14. d.) Molality (m)
m =
moles of solute
mass of solvent (kg)
e.) Parts per million
ppm =
mass of solute
mass of solution
x 106
15. ppm
1 ppm is one part by weight, or volume, of solute
in 1 million parts by weight, or volume, of solution.
In weight/volume (w/v) terms,1 ppm = 1g
m-3 = 1 mg L-1 = 1 μg mL-1
In weight/weight (w/w) terms,1 ppm = 1 mg kg-
1 = 1 μg g-1
18. How many moles of water form when
25.0 mls of 0.100 M HNO3 (nitric acid)
solution is completely neutralized by
NaOH (a base)?
EXAMPLE
19.
20.
21.
22.
23. SOLUBILITY
is the maximum amount of a substance
that will dissolve in a given amount of
solvent at a specific temperature.
24. Factors Affecting Solubility
There are two direct factors that affect solubility:
temperature and pressure.
• Temperature affects the solubility of both solids
and gases.
• Surface area does not affect how much of a solute
will be dissolved, but it is a factor in how quickly or
slowly the substance will dissolve.
• But pressure only affects the solubility of gases.
25. The Effect of Temperature on Solubility
Temperature has a direct effect on solubility.
For the majority of ionic solids, increasing the
temperature increases how quickly the solution can
be made.
As the temperature increases, the particles of the
solid move faster, which increases the chances that
they will interact with more of the solvent particles.
This results in increasing the rate at which a
solution occurs.
26. The Effect of Pressure on Solubility
The second factor, pressure, affects the solubility of a gas
in a liquid but never of a solid dissolving in a liquid.
When pressure is applied to a gas that is above the surface
of a solvent, the gas will move into the solvent and occupy
some of the spaces between the particles of the solvent.
This gas pressure factor is expressed in Henry’s law.
Henry’s law states that, at a given temperature, the
solubility of a gas in a liquid is proportional to the partial
pressure of the gas above the liquid.
27. The Effect of Surface Area on the Rate of
Dissolving
If we were to increase the surface area of a solid, then it
would have been broken into smaller pieces. We would do
this to increase how quickly the solute would dissolve in
solution
If you were to dissolve sugar in water, a sugar cube will
dissolve slower than an equal amount of tiny pieces of sugar
crystals. The combined surface area of all of the sugar
crystals have a much greater surface area than the one sugar
cube and will have more contact with the water molecules.
This allows the sugar crystals to dissolve much more quickly.
28.
29. Colligative Properties of Nonelectrolytes
and Electrolyte Solutions
depend on the concentration of solute particles
but not on their chemical identity.
The concentration of solute particles depends on
the amount of dissolved solute as well as on its
ability to dissociate to ions in solution
Colligative Properties
30. • Weak electrolytes – dissociate partially (weak
acids and bases)
• Strong electrolytes – dissociate completely
(soluble salts, strong acids and bases)
• Nonelectrolytes – do not dissociate (many
organic compounds)
• Nonvolatile Nonelectrolyte Solutions – No
dissociation; no vapor pressure (glucose, sugar,
…)
31. Vapor pressure lowering (ΔP)
• the vapor pressure of the solvent over the
solution (Psolv) is always lower than the vapor
pressure over the pure solvent (P°solv) at a
given temperature
Raoultʼs law
32. Raoult’s Law
• the vapor pressure of the solvent over the
solution is directly proportional to the mole
fraction of the solvent
• Followed strictly at all concentrations only by
ideal solutions
33. Boiling point elevation (ΔTb) and
freezing point depression (ΔTf)
• The solution boils at a higher temperature
compared to the pure solvent (the solution
has lower vapor P so it needs higher T to boil)
• The solution freezes at a lower temperature
compared to the pure solvent
34. Osmotic pressure (Π)
• Osmosis – the flow of solvent trough a semi
permeable membrane from a less
concentrated into a more concentrated
solution
• Semipermeable membrane – the solute
particles can’t pass through
35. The solvent tends to
flow into the solution
where the disorder is
greater
36. • Π is the hydrostatic pressure necessary to stop
the net flow of solvent caused by osmosis
Π = MRT
Π = (nsolute/Vsoln)RT
M – molarity of solution R – gas constant;
T – temperature in K
37. • The equation is the equivalent of the ideal
gas law (P = nRT/V) applied to solutions.
• Π is the pressure the solute would exert if it
were an ideal gas occupying alone the
volume of the solution.
38. • Osmosis is essential for controlling the
shape and size of biological cells and
purifying blood through dialysis
• Reverse osmosis – reversing the flow by
applying external pressure (used to purify
sea water)
