• Water is a compound that has many
properties
• It is necessary to sustain life
• Is the most abundant compound in
the cells of living things
• Plays a major role in maintaining
temperature
• Also important in making
solutions….
Solutions
What it a solution?
A solution is a homogeneous mixture
meaning that it is uniform throughout
and we cannot see the different
components.
This means that a sample from one part
of the solution is exactly the same as
a sample from any other part of the
solution.
Describing the Parts of a
Solution
Solute: the component of lesser
quantity (the stuff that is dissolved)
Solvent: the component of greater
quantity which usually defines the
physical state of the resulting solution
(the stuff that does the dissolving)
Using Water in Solutions
There are numerous compounds that will
dissolve in water –
Therefore water is known as the
Universal Solvent
Water Molecule = H20
-The H side has a positive
character
-The 0 side has a negative
character
How do we know if something will
dissolve in water?
• The rule is “like dissolves like”
• Depends on whether the substance is
polar or nonpolar.
What is “polar” and “nonpolar”?
• Polar molecules posititve and negative
charges in a molecule
Ex: water
What is “polar” and “nonpolar”?
• Non – polar molecules are those that do
not have the different positive and
negative sides.
• EX – oil
– Made up of non – metals
(hydrogen and carbon)
How Solids Dissolve
• Water breaks the + and - charged
pieces apart and surround them.
• EX : Salt = NaCl is an “ionic compound”
so we know it will dissolve in water.
We know it’s ionic because its made up of metal and
non-metal elements.
It has a polar character and will dissolve in water
How Solids Dissolve
H
H
H
H
H
When mixing salt with water the salt dissolves
in the water producing a homogenous mixture.
How much will dissolve?
• For most solutes there is a limit to how
much will dissolve in a given amount of
water.
• This is called solubility
• Saturated solution – once the maximum
amount of solute is dissolved (no more
will dissolve)
Types of Solutions
Not every solutions is made up
using water!
Gaseous solutions
gases in gases
air is a homogeneous mixture
of many gases
humid air is a result of water
vapor in the air.
Types of Solutions:
Liquid solutions
gases in liquids:
carbonated drinks are CO2 in
water
liquids in liquids:
vinegar is acetic acid in water
solids in liquids:
salt water is NaCl in water
Types of Solutions:
Solid solutions
liquids in solids:
dental fillings are a mercury-silver
amalgam (Hg is a liquid and
Ag is a solid)
solids in solids:
sterling silver is a mixture of copper
and silver
brass is a solid solution of zinc and
copper
Rate of Dissolving
The rate at which a given solute will
dissolve in a given solvent is
dependent upon three factors:
1. Temperature of the solution
2. Agitation of the solution
3. Size of the solute particles.
Rate of Dissolving
1.
Temperature of the solution
a.
b.
c.
Heating the solution increases the kinetic
energy of the solvent molecules so the solvent
molecules move faster.
With the solvent molecules moving faster,
they attack the solute particles more
frequently.
The solute particles are pulled into the
solution faster increasing the rate that they
dissolve.
Rate of Dissolving
2. Agitation of the solution
a.
Stirring the solution increases the interaction
between solvent molecules and the solute.
b.
The greater the interaction between solvent
and solute, the more rapid the rate of
dissolution.
Rate of Dissolving
3. Particle size and the rate of dissolution
a.
The smaller the particle size, the greater the
total surface area of the solute.
b.
Since the solvent attacks the solute particles
along the surface and edges, the greater the
surface area, the more the solute is exposed
to attack by solvent.
c.
The more frequently the solvent molecules
and attack the solute particles, the more
rapid the rate of dissolution.
Concentrations & Making
Solutions
• Concentration = how much solute is
dissolved in the solution
• Dilute = having a small amt. of solute
dissolved in the solution
• Concentrated = to having large amts. of
solute dissolved in the solution
• Need to express the concentration
based on percent
Percent by Mass
(solvent expressed as mass also)
Mass Percent:
% m/m =
Mass of solute (g)
Mass of solution (g)
X 100%
grams of solute
% m/m =(grams of solvent) +(grams of solute)x100%
Percent by Mass
(solution expressed as mass also)
Mass Percent:
% m/m =
% m/m =
Mass of solute (g)
Mass of solution (g)
12.3 grams of sugar
(61.5 grams of solution)
X 100%
x100%
= 0.2074198 X 100% = 20.74198 = 20.7% m/m
Preparing % m/v – solute is
solid, solvent is liquid
grams of solute
%m/v 
x 100%
mL of solution
21g of sugar
 0.0105 x 100%  1.05  1.1%m/v
2000mL of water
To determine the mass of solute needed to prepare a
solution the formula can be rearranged.
% soultion X grams of solution
grams of solute 
100
Example – what is the mass of a solute needed to prepare 250 g of a
5.0% m/m glucose solution?
5.0 X 250 grams of solution
grams of solute 
 12.5 g glucose
100
Preparing %v/v – both are liquids
• EX –
25.0 mL of alcohol are added to water to
a final volume of 100.0 mL = 25.0 %v/v
Always add the solvent “to a final volume
of” and not just combine the volumes of
solute and solvent.
Acids and Bases
Property of some aqueous
solutions is their ability to act
as an acid or base
Originally a chemical or solution
was classified as an acid if it
had the following 3 properties:
1. It has a sour taste
2. It turns a plant dye called litmus red
3. It eats away at more active metals like
zinc to produce a hydrogen gas.
Acids
battery acid
acid rain
stomach
acid
wine
vinegar
oranges
cheese
lemon juice
contains
contains
contains
sulfuric acid
sulfuric and nitric acids
hydrochloric acid
contains
contains
contains
contains
contains
tartaric acid
acetic acid
citric and ascorbic acids
lactic acid
citric and ascorbic acids
(ascorbic acid is vitamin C)
Properties of Bases
1. Bases also have a bitter taste. The
bitter taste of milk of magnesia
2. They turn the plant dye called litmus
blue.
3. Bases are also recognized because
they feel slippery or soapy.
Bases
cement and paper
fertilizers
Cleaning solutions
Baking soda
Liquid plumber
contain
contain
contain
contains
contains
calcium oxide (a base)
ammonia (a base)
ammonia (a base)
sodium bicarbonate (a base)
sodium hydroxide (a base)
Antacids
Alka-Seltzer
Di-Gel
Gaviscon
Maalox
contain
contains
contains
contains
contains
a variety of antacids
sodium bicarbonate
magnesium hydroxide
aluminum hydroxide
magnesium hydroxide
A scale was developed to relate the
acidity or basicity of a soltuion
• The scale related the available hydrogen ions in a
solution to a numerical value.
• It is based on on 0
14
• It’s called the pH scale
• The closer the pH value is to 0, the stronger the acid.
• The closer the pH value is to 14, the stronger the base.
• If the pH value is in the middle, or 7, the pH is neutral
Solutions may be:
strongly acidic (0 - 2),
weakly acidic (2 - 7),
neutral (pH=7),
weakly basic (7 - 12),
strongly basic (12 - 14).
More about “litmus”
Litmus paper can be used to indicate if a
solution is acidic or basic.
However, it does not indicate “how acidic” or
“how basic”.
What is litmus?
• Litmus is one of a large number of organic
compounds (it is actually extracted from
certain mosses) that change colors when a
solution changes acidity at a particular point.
• Litmus is the oldest known pH indicator.
• It is red in acid and blue in base.
• Litmus is often impregnated onto paper to
make 'litmus paper.'
Properties of Acids
An acid can be
identified in the
laboratory because it
turns a plant pigment
called litmus red.
A base can be identified in
the laboratory because
it turns a plant pigment
called litmus blue.
Measuring pH
pH indicators can also be impregnated
onto paper and used to determine pH.
Paper, called pHydrion paper, is
impregnated with a universal indicator.
It can be used to determine the
approximate pH over a full range.
More about “litmus”
Litmus paper can be used to indicate if a
solution is acidic or basic.
However, it does not indicate “how acidic” or
“how basic”.
What is litmus?
• Litmus is one of a large number of organic
compounds (it is actually extracted from
certain mosses) that change colors when a
solution changes acidity at a particular point.
• Litmus is the oldest known pH indicator.
• It is red in acid and blue in base.
• Litmus is often impregnated onto paper to
make 'litmus paper.'
Properties of Acids
An acid can be
identified in the
laboratory because it
turns a plant pigment
called litmus red.
A base can be identified in
the laboratory because
it turns a plant pigment
called litmus blue.
Measuring pH
pH indicators can also be impregnated
onto paper and used to determine pH.
Paper, called pHydrion paper, is
impregnated with a universal indicator.
It can be used to determine the
approximate pH over a full range.
Kinds of pH paper
pH Color Chart
pH & Buffers
• A buffer keeps something where it should
be.
• It buffers adverse swings. It shields,
cushions and protects.
• Is necessary to control any change
in pH in some systems
• Especially in biological systems which
need to control pH
• Living systems have buffering systems in
place
In order to maintain pH at a constant re
buffering of the system in a pond
Buffers
• Buffers tie up
foreign acid and
base
• There is a limit as to
how much acid or
base a buffer can
absorb
• This is called buffer
capacity
•A buffer would be used to maintain
the pH of a product within a narrow
range.
•Buffers reduce the variation in the
pH of a product, as shown on the
graph