Solutions
Solutions Classification
are
homogeneous
mixtures
of Matter
Solute
A solute is the dissolved substance in a
solution.
Salt in salt water
Sugar in soda drinks
Carbon dioxide in soda drinks
Solvent
A solvent is the dissolving medium in a
solution.
Water in salt water
Water in soda
Types of Solutions
Solution – is a homogeneius mixture of substances in the
same physical state. The substances are uniformly
distributed. Can contain atoms, ions, or molecules.
Solid in Solid → Brass (zinc with copper) A.K.A. Alloy
Gas in Gas → Air
Liquid in Liquid → Alcohol in water
Solid in Liquid → Salt in water
Gas in Liquid → Soda (CO2 in Water)
A substance dissolved in water is known as an aqueous
solution
Concentrated vs. Dilute
Concentrated- Having more solute particles per solvent particles.
Dilute – Having more solvent particles per solute particles.
Suspensions & Colloids
Suspensions and Colloids
Suspensions and colloids are NOT solutions.
Suspensions: The particles are so large that
they settle out of the solvent if not
constantly stirred.
Colloids: The particles intermediate in size
between those of a suspension and those of a
solution.
The Tyndall Effect
Colloids scatter
light, making a
beam visible.
Solutions do not
scatter light.
Which glass
contains a colloid?
colloid
solution
Electrolytes vs. Nonelectrolytes
The ammeter measures the flow of electrons (current)
through the circuit.
If the ammeter measures a current, and the bulb
glows, then the solution conducts.
If the ammeter fails to measure a current, and the
bulb does not glow, the solution is non-conducting.
Definition of Electrolytes and
Nonelectrolytes
An electrolyte is:
A substance whose aqueous solution conducts
an electric current.
A nonelectrolyte is:
A substance whose aqueous solution does not
conduct an electric current.
Try to classify the following substances as
electrolytes or nonelectrolytes…
Electrolytes?
1.Pure water
2.Tap water
3.Sugar solution
4.Sodium chloride solution
5.Hydrochloric acid solution
6.Lactic acid solution
7.Ethyl alcohol solution
8.Pure sodium chloride
9.
ELECTROLYTES:
NONELECTROLYTES:
Tap water (weak)
Pure water
NaCl solution
Sugar solution
HCl solution
Ethanol solution
Lactate solution (weak)
Pure NaCl
But why do some compounds conduct electricity in
solution while others do not…?
Answers to Electrolytes
Dissolution of sodium Chloride
How Ionic solids dissolve
H
H
H
H
H
Rules for Determining Solubility
Table G
1. Determining Solubility:
• Saturated Solution → Point is on the line
• Unsaturated Solution → Point is below the line
• Supersaturated Solution → Point is above the line
2. Interpreting the graph table G
•Units on the graph are grams of solute/100g of water.
•If problem calls for g/200g of water or g/50g of water, double
or half the grams of solute, respectively.
Ex. 50g/100g of water
25g/50g of water
100g/200g of water
150g/300g of water
Solubility
Practice Problems
1.
How many grams of NaCl are needed to make a
saturated solution at 60˚C?
2. How much NaNO3 is required to make a saturated
solution in 100g of water at 60˚C? In 200g of water at
60ºC?
3. How much KNO3 will precipitate out of solution when a
saturated solution of KNO3 is cooled from 70˚C to 10?
4. At 60˚C what type of solution is 35g of KNO3 in 100g of
water? In 50g of water?
Solubility Chart
Saturation of Solutions



A solution that contains the maximum amount of
solute that may be dissolved under existing
conditions is saturated.
A solution that contains less solute than a
saturated solution under existing conditions is
unsaturated.
A solution that contains more dissolved solute
than a saturated solution under the same
conditions is supersaturated.
Saturation and Equilibrium
Solubility Trends




The solubility of MOST solids increases
with temperature.
The rate at which solids dissolve
increases with increasing surface area of
the solid.
The solubility of gases decreases with
increase in temperature.
The solubility of gases increases with
the pressure above the solution.
Therefore…
Solids tend to dissolve best when:
o Heated
o Stirred
o Ground into small particles
Liquids & Gases tend to dissolve
best when:
o The solution is cold
o Pressure is high
Heat of Solution
The Heat of Solution is the amount of heat
energy absorbed (endothermic) or released
(exothermic) when a specific amount of
solute dissolves in a solvent. Table I
Substance Heat of Solution
(kJ/mol)
NaOH
-44.51
NH4NO3
+25.69
KNO3
+34.89
HCl
-74.84
Molarity
The concentration of a solution
measured in moles of solute per liter of
solution.
mol = M
L
Molality
The concentration of a solution in moles
of solute per kilogram of solvent.
mol =
kg
m
Since the most common solvent, water,
has a density of 1 kg/L, one kilogram
of water is the same as one liter of
water!
Ways of Expressing
Concentration
Mass Percentage, ppm, and ppb
• All methods involve quantifying amount of solute per
amount of solvent (or solution).
• Generally amounts or measures are masses, moles or
liters.
• Qualitatively solutions are dilute or concentrated.
• Definitions:
mass of component in solution
mass % of component 
 100
total mass of solution
mass of component in solution
ppm of component 
106
total mass of solution
• Parts per million (ppm) can be expressed as 1 mg of
solute per kilogram of solution.
– If the density of the solution is 1g/mL, then 1 ppm = 1 mg
solute per liter of solution.
• Parts per billion (ppb) are 1 g of solute per kilogram of
solution.
mass of component in solution
ppb of component 
 109
total mass of solution