Download Grade 7 Science

Grade 7 Science
Solutions
Solutions… a review
A homogeneous mixture appears as ONE
substance
Examples:
tap water
vinegar
gold jewelry
Solutions have 2 parts:
Solute
The substance
that dissolves
(found in less
amounts)
Eg. Lemon juice
in Lemonade
Solvent
The substance in
which the solute
dissolves (found in
the greatest
amounts)
Eg. Water in
lemonade
Examples:
Solution
Solute State Solvent State
brass
copper solid
iron
solid
vinegar
Acetic liquid
acid
oxygen gas
Water
liquid
air
Carbonated Carbon gas
water
dioxide
Seawater
salt
solid
nitrogen gas
water
liquid
water
liquid
Dissolving...
To mix completely ie. the solute dissolves
into the solvent.
The physical properties of the solute and
the solvent combine into one set of
properties.
Some substances are able to dissolve
better than others.
Soluble or Insoluble
A substance that is soluble is able to
dissolve in a solvent.
Eg. sugar is soluble in water
A substance that is insoluble is not able to
dissolve in a solvent.
Eg. sand is insoluble in water
Soluble or Insoluble?
soluble
insoluble
The Particle Theory of
Matter
states that “there are attractive
forces between the particles”
Some of these forces are strong
and some are weak
In order to dissolve,
the particles must be
more strongly
attracted to the
particles of the solvent
than to themselves.
This means that the
solute is soluble in that
solvent.
If the particles of the solute
are more attracted to their
own particles than the
solvent particles, dissolving
does NOT occur.
The solute is said to be
insoluble in that solvent.
(ie. Mechanical)
Sand and rocks
are insoluble in
water
Solvent or Not?
Some materials are good
solvents for some solutes
but not others.
For example:
Oil is insoluble in water
but soluble in gasoline.