Solutions, Acids,
and Bases
Chapter 8
Parts of a solution

Solute
 The substance that
is dissolved into the
solution.
 examples:
• Sugar in kool-aid
• Salt in salt water
• CO2 in pop

Solvent
 The substance that
does the dissolving
in a solution.
 examples:
• Most common is
water.
Dissolving
 Three ways to dissolve a solute
in a solvent:
1. Dissociation
2. Dispersion
3. Ionization
1. Dissociation
The process in which an ionic
compound separates into ions in a
solution. (physical change)
 Example: salt in water

2. Dispersion
 Breaking
the solute into small
pieces and spreading
throughout the solvent.
 Ex. Sugar in water
 Physical change
3. Ionization
 The
process in which neutral
molecules lose or gain
electrons.
 Chemical change
 Ex: HCl in water page 230
Conductivity
 Many
solutions can conduct an
electric current if electrolytes
are present. (ions)
 Electrolytes = substances that
will conduct an electric current
when dissolved. Ex. NaCl, KCl,
MgBr2
Freezing Point Depression

Lowering the
freezing point of
water by the
addition of a solute
 ex. salt.
 Used on icy roads in
winter
 Ice-cream
Boiling point elevation

The addition of a
solute to a liquid
solvent will usually
raise the boiling
point of the solvent.
 Adding salt to boil
water when cooking
Heat of Solution
 A measure
of the amount of energy
either absorbed or released when a
solute dissolves in a solvent.
 Can be endothermic or exothermic.
Rate of Solution

Speed at which
solute dissolves in a
solvent.
 1st Stirring the
solution. Helps to
move the solute
particles away from
the solid solute.
Other factors:
2nd : Powdering the
solute.
 Increases the
surface area

3rd : Heating the
solution.
 Speeds up the
molecules

Concentration
 Concentrated
 Dilute
 A large
 A little
amount
of solute
dissolved in a
solvent
bit of
solute dissolved
in a solvent
Saturation
A solution that contains all the solute it
can possibly hold at a given
temperature is said to be saturated.
 Unsaturated = contains less solute than
it can possibly hold
 Supersaturated = a solution that holds
more solute than it should at a given
temperature.

Supersaturation example:
 Sodium
acetate in
water.
 Used in
commercial
hand
warmers.
Insoluble
A
substance
that will
NOT
dissolve in
water.
“Like dissolves like”
Nonpolar solvents will dissolve nonpolar
solutes.
 examples: benzene & acetone
 Polar solvents will dissolve polar solutes

2 factors that affect solubility:

1.Temperature
 2. Pressure
 Increase in temp
 Usually has little, if
generally increases
any, effect on solid
solubility of a solid in
and liquid solutes.
a liquid
 Increase in pressure
 Increase in temp
increases the
decreases solubility
solubility of a gas in
of a gas in a liquid.
a liquid.
Specific concentration
 Can
be defined as percent by
volume or percent by mass
 Example: 3% hydrogen
peroxide or 25% fruit juice.
MOLARITY
Acids

Very important
chemicals in
everyday life
processes.
Properties of acids:
1.
2.
3.
4.
Sour taste (never taste a chemical)
All contain hydrogen
Also called “proton donors”
React with active metals to produce
hydrogen gas. (exp. 21)
Zn +
2HCl
ZnCl2 + H2
Indicators


A.
B.
C.
D.
Chemicals used to identify acids and
bases by changing color.
ACIDS:
Litmus paper (blue to red)
Phenolphthalein (colorless)
Methyl Orange (orange to red)
Bromothymol Blue (changes to yellow)
Common acids
Sulfuric (H2SO4) used in car batteries
 Nitric (HNO3) also fertilizers
 Hydrochloric (HCl) stomach acid
 Carbonic (H2CO3) carbonated drinks
 Acetic (HC2H3O2) vinegar

Bases

Also very important in everyday
processes.
Properties of Bases:
Taste bitter; feel slippery
 Contain hydroxide (OH) ions.
 Known as “proton acceptors”
 Phenolphthalein turns bright pink
 Red litmus paper turns blue
 Bromothymol blue turns blue
 Methyl orange turns yellow

Common bases:
Sodium hydroxide NaOH making soap;
drain cleaners
 Potassium hydroxide KOH battery
electrolyte
 Calcium hydroxide Ca(OH)2 making
plaster and drywall
 Magnesium hydroxide Mg(OH)2antacids

Solutions of acids and bases
pH scale (page 247)
 A numerical scale developed to
measure the relative strengths of acids
and bases
 Ranges from 0 to 14
 0 is the strongest acid
 14 is the strongest base.

What happens when an acid and
a base combine?
Always forms water and a salt.
 Salt = ionic compound formed when a
positive ion of a base combines with a
negative ion of an acid.
 Neutralization.
 These are double replacement
reactions. Examples: (on board)

What determines if an acid is
classified as “strong” or weak?
Which is stronger? 1 M acetic acid or
1M hydrochloric acid?
 Strength is determined by how well the
acid or base dissociates into solution.
 Strong acids and strong bases are good
electrolytes.

Buffers

A mixture of a weak
acid or weak base
with its salt.
 Resists large
changes in pH.
 Examples:
– Bicarbonate ions in
your blood stream.
Assignment
 Pages
257-258
 1-10, 11, 13, 16, 20, 22, 23, 24,
27, 30, 31, 32