Name appropriate apparatus for the measurement of time, temperature, mass and volume, including burettes, pipettes and measuring cylinders 2.2 Purity Methods of purification • Describe and explain methods of purification by the use of a suitable solvent, filtration, crystallisation and distillation (including use of a fractionating column). (Refer to the fractional distillation of petroleum and products of fermentation) • Suggest suitable purification techniques, given information about the substances involved

1. Presented by: Mrs. Saima

4.  2.1 Measurement
• Name appropriate apparatus for the measurement of
time, temperature, mass and volume, including
burettes, pipettes and measuring cylinders
 2.2 Purity
Methods of purification
• Describe and explain methods of purification by the
use of a suitable solvent, filtration, crystallisation
and distillation (including use of a fractionating
column). (Refer to the fractional distillation of
petroleum and products of fermentation)
 • Suggest suitable purification techniques, given
information about the substances involved

5.  A solution in chemistry is a homogenous mixture of
two or more substances.
 The substance which is dissolved is called a solute.
 The substance in which the solute is dissolved is
called a solvent.
 The maximum amount of solute that can dissolve in a
known quantity of solvent at a certain temperature is
its solubility.
 A pure substance would be made of a single
substance and is not mixed with something else eg.
pure water, gold which is not mixed with something
else
 An impure substance has two more substances mixed
together eg. mixture of salt and sand.
 Suspension is when a solute is not homogenised with
a solvent and its particle

7.  Purity assessment from melting
point/boiling points
The melting point of a substance is the
temperature in which the substance
melts. Similarly, the boiling point of a
substance is the temperature at which
it boils.
 Interestingly, the boiling point and
melting point of a substance can give us
an indication of how pure it is. The
table below summarizes this quite well

8.  A pure substance have
definite, sharp melting
point and boiling point.
These are different for each
substance. You can identify
a substance from its mp/bp
 When a substance contains
impurity
I. Its melting point falls and
boiling point rises
II. It melts and boils over a
range of temperature and
does not have a sharp
melting point
III. Recall heating curves →

10.  Mass:
Scale, balance, top pan
balance, digital
balance etc
 Time:
Clock, stop watch
 Temperature:
Thermometer
 Volume:
?
Beaker?
Measuring cylinder?

12.  Pipettes and burettes are more accurate than
measuring cylinder.
 Measuring cylinder is quicker and easier
 If you need to pour something quickly you must
use measuring cylinder,
 If you need an accurate measurement of volume
of liquid, pipette or burette must be used.
 Pipettes are usually used to add a fix volume for
example 5,10,25 cm3.
 Burette can be used for measuring variable
volumes of liquids accurately like 11.2 cm3, 21.9
cm3 etc

13.  Filtration:
To remove an insoluble solid from a liquid/solution
 Decanting :
To separate a liquid from insoluble solid
 Evaporation :
To separate a soluble substance (solute) from a solution.
 Crystallization :
To separate a soluble substance (solute) from a solution in
the form of crystals.
 Simple distillation:
To separate a solvent (liquid) from the solution leaving
behind solute.
 Fractional distillation:
To separate a mixture of liquids from each other on the bases
of different boiling points

14.  Filtration
Filtration is carried
out by pouring
the mixture into
a funnel covered
by a filter paper.
Whilst the liquid
will pass through
the filter, solids
will get caught,
thereby
separating
them.

15.  Decanting is the
simple process of
letting insoluble
solids settle in
the liquid before
gently pouring it
out later.

16.  This is a simple
process of separating
a solute from a
solution. Simply let
the solvent
evaporate off and it
will leave the solids
behind. Solution is
heated in an
evaporating dish over
a Bunsen burner and
tripod until all
solvent evaporates,
leaving behind the
solid solute.

17.  This technique is
used to separate a
soluble solid from
a solution. It works
by heating the
solution to
crystallisation
point and then
slowly cooling it.
The soluble salt
will crystallize on
cooling due to
decrease in
solubility at low
temperature.

18.  2.1 Measurement
• Name appropriate apparatus for the measurement of
time, temperature, mass and volume, including
burettes, pipettes and measuring cylinders
 2.2 Purity
Methods of purification
• Describe and explain methods of purification by the
use of a suitable solvent, filtration, crystallisation
and distillation (including use of a fractionating
column). (Refer to the fractional distillation of
petroleum and products of fermentation)
 • Suggest suitable purification techniques, given
information about the substances involved

19.  Copy the objectives
 Copy the questions on topic 2.3 and Answer
them.
 Raise your hand when finished