When will solute and solvent create a solution?
Think about the Chromatography Lab!
”Like dissolves like”
DHsolution = DH1+DH2+DH3
What happens if…
Polar solvent and
solute
Nonpolar solvent
and solute
Polar solvent and
nonpolar solute
Nonpolar solvent
and polar solute
DH1(solv) DH2 (solute) DH3
DHsolution
Outcome?
Why do solutions form if DH is positive?
When a salt dissociates, the energy associated
with the separation of ions(lattice energy) is often
so large resulting in an endothermic DHsoln
 Coulomb’s Law: F = q1q2/r2
 If ions are highly charge, soluble or insoluble?

What factors effect solubility?

Pressure (for gas solute only)

Henry’s Law C= kP

The elevation of Lake Havasu is 400 feet, and
Lake Tahoe is 6200 feet. If the water
temperatures are the same, which lake has a
lower concentration of oxygen gas?
For aqueous solutions, temperature …
Many solids increase in solublity as
temperature increases, some don’t
Are less soluble as temperature increases, why?
Gases

In our BORAX crystal
experiment we relied
on solubility. What
does it measure?

amount of solute
dissolved in a given
amount of solvent –
typically measured in
g solute/100 g
solvent
•Saturated
•Unsaturated
•Supersaturated
Do Now:


What is vapor pressure? What factors impact
it? What are colligative properties?
What will happen over time in the picture?
Water
Aq. soln
Closed environment
Colligative properties?


Properties of a solution that depends on the
number of particles in a given volume of
solvent and not on the mass of the particles.
Physically we apply this principle at home. In
the laboratory, this is a means to accurately
determine the molar mass of a solute.
Compare the pure solvent and solution
depicted below
The addition of a nonvolatile solute (right)
decreases the number of solvent molecules
per unit volume and lowers solvent’s
escaping tendency, thereby lowering vapor
pressure
Vapor Pressure Reduction


Raoult’s Law
Psolution = xsolventPsolvent (nonvolatile solute)
X is mole fraction
What if the solute is volatile?
Psolution = xsolventPsolvent + xsolutePsolute
Applies to an ideal solution
TRY WITHOUT CALCULATOR!
A solution is prepared by mixing 5.81 g acetone
(C3H6O, molar mass = 58.1 g/mol) and 11.9 g
chloroform (HCCl3, molar mass = 119.4 g/mol). At
35°C, this solution has a total vapor pressure of
260. torr. Is this an ideal solution? Explain why or
why not.
The vapor pressures of pure acetone and pure
chloroform at 35°C are 345 and 293 torr,
respectively.

How does the freezing
point and boiling point of
a solution compare to the
pure solvent? Explain at
molecular level.
Remember …
1. at phase change equilibrium is established
2. boiling/freezing point are
temperatures when the vapor
pressure of the solid (fp) or liquid(bp)
are equal to the external atmospheric
pressure.

Boiling Point Elevation
DTb = i kb m

Freezing Point Depression
DTf = i kf m

The molar mass of an unknown hydrocarbon
is determined by dissolving in CHCl3. The
solution is prepared by mixing 100. grams of
CHCl3 and 0.600 gram of the hydrocarbon is
-64.0 °C. The molal freezing-point depression
constant of CHCl3 is 4.68 °C / molal and its
normal freezing point is -63.5 °C. Calculate
the molecular weight of the hydrocarbon.
What is osmosis?

Osmosis is the spontaneous movement of solvent
molecules through a semi-permeable membrane
from an area of higher solvent concentration to an
area of lower solvent concentration .
Osmotic
pressure
Solution
Pure
Solvent
Semipermeable membrane
Solution
Pure
Solvent
Osmotic Pressure
 P = iMRT
• What concentration of sodium chloride in water is needed to
produce an aqueous solution isotonic with blood (π= 7.70
atm at 25°C)?
• What would happen if a pressure that exceeded osmotic
pressure was applied to the solution?
Osmotic Pressure - SomeApplications


Water Purification (Reverse Osmosis)
Physiology
Water Transport in Plants
(Osmosis pushes,
hydrogen bonding pulls)
 Food Preservation
(salty,sugary)

Van’t Hoff Factor, i
What is it?
What is ion pairing?
What is the effect of
concentration?
Formulas:

Mass % = mass A/ total mass x 100
Molarity = moles solute/L solution
Molality = moles solute/kg solvent
Mole fraction = moles A/ total moles

Psolution = xsolventPsolvent + xsolutePsolute



DT = ikm
 P = iMRT

DO NOW!
 In
preparing a solution …
 are
moles conserved?
 is volume conserved?
 is mass conserved?
What is a colloid?
=
Particle Size
1.
2.
3.
Solution
< 1 nm
Colloid
1 – 100 nm
Suspension > 100 nm



Solution Does not settle, passes through
filter paper, does not scatter light
Colloid Does not settle, passes through
filter paper, will scatter light
Suspension Will settle on standing,
separated by filter paper, will scatter light
Tyndall effect - effect of light scattering on
particles in colloid systems
Some colloids-
• Jello (Liquid dispersed phase in solid
medium)
•
Aerosol sprays (Liquid dispersed
phase in gaseous medium)
• Whipped Cream (Gaseous dispersed
phase in liquid medium)
• Mayonnaise (Liquid dispersed phase in
liquid medium)
Dispersed phase
Medium / Phases
Gas
Gas
Liquid
Solid
Liquid
Solid
All gases are
Liquid Aerosols. Solid Aerosols
miscible in each Ex- Fog, Mist, Hair Ex- Smoke,
other so no colloid sprays.
Clouds, Air
Particles.
Foam
Ex- whipped
cream, Shaving
cream
Emulsions
Sol
Ex- Mayonnaise, Ex- Blood and
Milk, Hand creams.pigmented ink,
Milk of magnesia.
Solid foam
Gel.
Solid Sol
Ex- Pumice stone, Ex- Gelatin, Jams, Ex- Metals alloys,
Styrofoam
Jellies, Jello
Pearl