Kool Aid Jello
Chapter
How to make super kool
aid or extreme jello
Kool Aid drinks are solutions
• Solutions are homogenous mixtures of two
or more pure substances in a single phase
• Contains a solvent and solute
– Solvent: dissolving medium (water)
– Solute: dissolved substance(salt)
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Particle sizes are the smallest
Will not separate while standing
Do not filter
Do not scatter light
Colligative properties are affected
Solutions
Muddy water is a
Suspension
• Suspensions are heterogeneous
mixtures that have the largest
particles of all mixtures
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Will separate upon standing
Can be filtered
Do scatter light
Colligative properties are unaffected
Examples: Muddy water, Cu Lab.
Suspensions
Milk/Gelatins are Colloids
• Colloids are homogeneous mixtures that
are medium in size.
• Particles remain dispersed in liquid due to
random particle motion of surrounding
molecules.
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Will separate very slowly or not at all
Will not filter
Will scatter light
Colligative properties are unaffected.
What is this scattering light?
Tyndall Effect
• Light bounces off objects it cannot
pass through, is scattered by
objects, or passes right through
objects.
• The scattering of light as it passes
through a transparent medium is
called the Tyndall Effect.
• When focused light is shined on a
homogeneous solution the light will
not be scattered; it will pass right
through.
• When focuses light is shined on a
colloid the light will be scattered
and no longer as focused.
What are they?
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Oil and vinegar salad dressing?
Gelatin?
Starch in water?
Smoke in air?
Salt in water?
Clay in water?
Food coloring in water?
• Carbon dioxide in water?
• Steam in air?
• Table sugar in water?
• Milk?
• Bleach?
• Ammonia?
• Tea?
More on Solutions
The M’s of it all
Concentration
• Different solutions can have different
concentrations by dissolving more or
less solute in a given amount of
solvent
Concentrations is scaled on molality
and molarity
Molarity
• Molarity(M) is defined as the number
of moles of solute per liter of solution
• M=moles of solute/liters of solution
Molality
• Molality(m) is defined at the number
of moles of solute divided by the
number of kilograms of solvent
• M = moles of solute/kg of solvent
Solubility
• Solubility is the chemical process in
which chemicals are able to dissolve
each other (able to mix well)
• The ability to mixed is determined by
the types of bonds holding the
chemical together.
• “like dissolve like”
Miscible
• Alcohol and water mix quite readily due
to the stronger forces of attraction
between the solvent and solute.
• Both water and alcohol are polar bonds
and therefore can dissolve each other.
• Miscible is the ability to dissolve each
other due to similar bonds
Immiscible
• Immiscible chemicals have opposite
forces of attraction and therefore
DO NOT MIX
• Oil and water
• Mystic sand and water
Colligative
Properties of
Solutions
Not freezing when cold or
boiling when hot!
Colligative Properties
• Some of the properties of solutions
do not depend on the amount and
type of solute present in solution.
– Ie food coloring doesn’t affect the
boiling point of water (much)
• Properties that depend on the
concentration of solute particles but
not on their identity are called
Colligative properties.
Electrolyte and non
Electrolyte
• Electrolytes are substances that
dissolve in water to give a solution
that conducts an electric current
– Sports drinks and salt water
– Ionic compounds are usually strong
electrolytes because they separate
completely in water
– Covalent compounds can be strong,
weak or non electroyltes
• Non-electrolytes: a liquid or solid
substance that does not allow the
flow of an electric current, either in
solution or in its pure state, such as
water or sucrose.
• Nonvolatile substance is one that
has little tendency to become a gas
under existing conditions
Freezing point depression
The freezing point of a 1 molal solution
of any nonelectrolyte solute in water
is found to be 1.86 degrees lower
than the freezing point of water.
Thus 1 mole of solute in 1 kg of water
will equal -1.86 degree C
• If you had 2 moles of solute in 1 kg of
water the freezing point would be
-3.72 degree C.
• This is 1.86 X 2
• This 1.86 degree C/m is known as
molal freezing point constant (Kf)
• Molal Freezing point constant is the
freezing point depression of the
solvent in a 1 molal solution of a
nonvolatile, non electrolyte solute.
Kf for substances
• Each solvent has its own
characteristic molal freezing point
constant.
• Kf is most accurate at 1 atm.
• Kf for water is -1.86, for Ether is -1.79
and Acetic Acid -3.90
• The freezing point depression, ∆tf, is
the difference between the freezing
points of the pure solvent and a
solution of a non electrolyte in that
solvent, and it is directly proportional
to the molal concentration of the
solution.
• ∆tf=Kf*m
Did you know?
• Some animals are able to survive freezing
temperatures by producing natural
antifreezes, substances that lower the
freezing point of a liquid. In many freezetolerant insects, the antifreezes are
alcohols and sugars.
• Examples are box turtles, painted turtles
and garter snakes, sugar maples and
white spruce.
Sugar Maple
• Taking a sugar
substance from a tree
can be used to
create maple syrup
• The maple syrup
aqueous solution boils
at 219 degree F
• That is 7 degree
higher than water.
• Why?
Boiling point elevation
• The boiling point of a liquid is the
temperature at which the vapor
pressure of the liquid is equal to the
prevailing atmospheric pressure.
• Vapor pressures of solutions
containing nonvolatile solute is lower
than the vapor pressure of the pure
solvent.
• This means that more heat will be
required to raise the vapor pressure
of the solution. Thus, the boiling point
of a solution is higher than the
boiling point of the pure substance.
• The molal boiling point constant, Kb,
is the boiling point elevation of the
solvent in a 1 molal solution of a
nonvolatile, non electrolyte solute.
Boiling point elevation
• Boiling point elevation, ∆tb, is the
difference between the boiling
points of the pure solvent and a
nonelectrolyte solution of that
solvent, and it is directly proportional
to the molal concentration of the
solution.
• ∆tb=Kb*m
What about Electrolytes?
• Electrolytes break apart into ions.
Each ion has an effect on boiling
point and freezing points. If a
solution has more or less ions it will
change the boiling points and
melting points even more.
Ions
• ∆tb or f=Kb or f*m*n
• m=molality
• n = number of ions
– Example
• NaCl = Na+ and Cl- = 2 ions=2 n
• MgCl2= Mg+ and 2 Cl- =3 ions =3 n
• Fe2(SO4)3=2 Fe+3 and 3 SO4-2 = 5 ions or 5 n
Example
• What is the new freezing point of 200
mL of water (Kf = -1.86 oC) if195 g of
sucrose (C12H22O11) are added to it?
195 g sucrose
= .570 moles
342 g
.570 moles
= 2.85 molal
.200 Kg
Now we can plug into ∆tf=Kf*m
∆tf=(-1.86oC) * (2.85 molal)
∆tf= -5.3010C
This means the water will freeze
5.301oC below its freezing point.
∆tb or f=Kb or f*m*n
• Same as other formula, just adding
n.
• NaCl, K2SO4, AlCl3, Al2O3.