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Properties of Mixtures: Solutions & Colloids - Coggle Diagram
Properties of Mixtures: Solutions & Colloids
Types of Solutions
Saturated
The
maximum amount
of solute has dissolved in a solvent at a specific temperature, and
some undissolved solute
particles remain in the solution.
Undissolved Solute ⇌ Dissolved Solute
Reversible Reaction
Unsaturated
All solute particles
are dissolved because the solution contains
less solute
than the maximum amount soluble at a specific temperature.
Supersaturated
The solution contains
more
than the equilibrium concentration of solute, making it
unstable
, and any disturbance will cause excess solute to
crystallize
immediately.
Equilibrium is established at a certain temperature.
Heat
increases
the amount of solute dissolved, and lower temperatures cause
crystallization
.
Saturation is dependent on
volume
and
temperature
.
Physical State
The physical state of a solution is the
same
as the physical state of the solvent.
When given a solute and three solutions (saturated, unsaturated, supersaturated), you can determine the
saturated solution
by adding the solid solute and observing the solution in which it remains
undissolved
.
Alloys
Mixtures of elements that have a
metallic character
are
solid-solid
solutions.
In a
substitutional alloy
like brass, atoms of zinc
replace
atoms of the main element, copper, at some sites in the lattice.
In an
interstitial alloy
like carbon steel, atoms of carbon fill some spaces
between
atoms of the main element, iron.
Intermolecular Forces
A solution is formed by breaking
solute-solute
attractions (endothermic
absorbing heat
) and
solvent-solvent
attractions (endothermic
absorbing heat
) and then forming
solute-solvent
attractions (exothermic
releasing heat
).
Ion-dipole
bonds are formed between ions and polar molecules, such as sodium and water.
Hydrogen
bonds are formed between hydrogen molecules and nitrogen, oxygen, or fluorine.
Dipole-dipole
bonds are formed between polar molecules, such as ethanal and chloroform.
Ion-induced dipole
bonds are formed between ions and nonpolar molecules, such as chlorine and hexane. The repulsion follows the dipole moment.
Dipole-induced dipole
bonds are formed between polar and nonpolar molecules, such as water and xenon.
Dispersion
bonds are formed between nonpolar molecules, such as octane and hexane.
The
hydration
(solvation by water) shells around an ion are oriented by
opposite
charges.
Solvation
is the process in which a solute particle is surrounded by solvent particles.
Hydration of an ion is always exothermic because
ion-dipole
forces are very strong.
Variable-Term-Formula Correlations & Trends
Endothermic
Absorption of Heat
ΔH
solution
> 0
Feels Cold
∆H
hydration
< ∆H
lattice
Exothermic
Release of Heat
ΔH
solution
< 0
Feels Warm
∆H
hydration
> ∆H
lattice
ΔH
solution
= ΔH
solute
+ ΔH
solvent
+ ΔH
mixture
Heat (enthalpy) of a solution is the
total enthapy change
that occurs when solute and solvent form a solution.
Charge Density
∆H
hydration
of an ion depends on the charge density, or ratio of
charge
to
volume
.
The
higher
the charge of the ion and
smaller
its radius, the
closer
the ion can be to the oppositely charge pole of the water molecule, and the
stronger
the attraction.
Decreases Down Group
Increases Across Period
∆H
solution
= ∆H
lattice
+ ∆H
ionhydration
For
ionic compounds
, the heat (enthalpy) of solution is the lattice energy plus the combined heats of hydration of the ions.
Solubility Trends
Solubility of
ionic solids
increases as temperature increases.
Solubility of
gases
decreases as temperature increases.
Solubility of
gases
increases as pressure increases because the particles collide with the liquid surface more often.
c = k • p
Solubility is the product of
Henry's Law Constant
and
partial pressure
of the gas.
Once opened, cans of soda go
flat
since the pressure of carbon dioxide in the air is less than that of the sealed can. Solubility decreases as CO2 bubbles out of the solution.
Concentration Units
Molality, m
Percent Mass, %
Molarity, M
Parts Per Million, ppm