You will be able to:
Describe the titration process
Determine the end point of
titration during neutralisation.
Titration is a very useful laboratory technique in which one
solution is used to analyse another solution. In acid-base
titration, a titrant (known concentration solution) is carefully
delivered from a burette to completely neutralise a known
volume of titree in a conical flask. An acid-base indicator is
Did you know?
used to detect the end of he titration when it changes colour.
The juice of purple
The at which this happens is called the end point. cabbage can act as an
The end point of neutralisation is achieved when all the OH- contains a chemical
ions combine with all the H+ ions in the solution to form water substance known as
which is neutral. changes colour when
the pH value of a
solution changes. In an
Since both reactants (acid and alkalis) and the products formed acidic solution, the
purple cabbage purple
(salt and water) are colourless, the end point of neutralisation cabbage is red or
can be determined by three methods as follow: purple in colour. In an
alkaline solution, the
colour is blue or green.
1. The use of acid-base indicators such as methyl orange, Other natural indicators
include carrot juice,
phenolphthalein and litmus. yellow ginger powder
and extracts from
2. Measurement of the pH values of the solution on the certain types of red or
computer interface during titration. yellow hibiscus flower.
3. Measurement of the electrical conductivity of the
solution during titration.
Indicator Colour in alkalis Colour in neutral solution Colour in acids
Methyl orange Yellow Orange Red
Phenolphthalein Light Pink Colourless Colourless
Litmus Blue Orange Red
Procedure of Acid-Base Titration
1) Transfer 25 cm3 of sodium hydroxide, NaOH, into a
conical flask by using pipette.
2) Put a few drops of phenolphthalein into the sodium
hydroxide, NaOH solution.
3) Clamp the burette vertically on the retort stand and
fill in with 1 mol dm-3 hydrochloric acid, HCl.
4) Place the conical flask containing sodium hydroxide
solution on top of the white tile at the base of the
5) Record the initial volume of the hydrochloric acid in
6) Add the hydrochloric acid into the conical flaks
slowly until the pink solution changes to colourless
while continuously shaking the conical flask.
7) Record the final volume of the hydrochloric acid on
8) Repeat the titration process three times to obtain
more accurate volume of hydrochloric acid at the end