3.4 Solutions
LEARNING POINTS
1
-Investigate and
describe dissolving
-Learn that soluble
and insoluble
substances cause
water pollution
2
.-Investigate how to
separate a solution
-Measure liquids
-Learn that dissolving
is a reversible process
3
-Decide on the type of
scientific enquiry to
use to investigate a
question
WHAT IS CONCENTRATION?
.
WHAT IS A
SOLUTION?
A solution is a mixture formed
when a solute dissolves in a
solvent. Salt water is an
example of a solution.
WHAT IS A
Mixture?
-In a mixture, substances
are generally just mixed and
are not completely dissolved
-A mixture is a material composed of two
or more substances that are physically
combined but not chemically bonded.
WHAT IS
VOLUME?
The volume of a 3D shape is a
measure of the amount of
space or capacity it occupies
e.g. a can of fizzy drink can
have a volume of 330 ml.
CALCULATING
CONCENTRATION
Concentration
mass of solute
=
volume
Glossary
Think and fill in the blanks
Salt added to water:
The solute is the ______
The solvent is the ________
This makes a _________
The salt is _____ as it has ____________
CALCULATION: EXAMPLE
6 g of sodium hydroxide is dissolved in 2
of water. Calculate the
concentration of the sodium hydroxide solution formed.
6 g of solute
2
of water
=
3
Please draw particle box for solid which has dissolved.
Show the particles of solid and water using different
colour
DIFFERENT
UNITS
There are different units for
Volumes used when calculating
measuring volumes. Some pieces
concentrations must be converted
of equipment use ml, whilst others
into
use
. In this case, the units
are equal.
300 ml = 300
.
1
= 1000
Retrieval questions
1.What is dissolving
2. Can all solids dissolves
3. a.Name the two parts of solution
b. Give an example of each of the two parts
4. Why is a solution a mixture?
Have you ever think about the methods of
separating a solution ????
Separating a solution
Evaporation
Evaporation is used to separate a soluble solid (i.e. a solid that
dissolves) from a liquid. For example, copper sulfate is soluble in water –
its crystals dissolve in water to form copper sulfate solution.
During evaporation, the water evaporates away leaving solid copper
sulfate crystals behind.
Correct the sentences
1. When we stir into tea, the sugar melts/dissolves.
2. The solid part of a solution is the solute/solvent.
3. The liquid part of solution is the solute/solvent.
4. Salt is a soluble/insoluble substance. (soluble)
5. Sand is a soluble/insoluble substance
6. A solution is/is not a mixture because we can separate
7. We can separate salt from a solution by
condensation/evaporation.
Think about factors affecting the rate of
dissolving
The three main factors that affect the rate of
dissolving
are temperature, particle size, and stirring. Higher
temperature, smaller particle size, and stirring all
increase the speed at which a solute dissolves in a
solvent.