EXPERIMENT 1
Title
: The Potentiometric Titration of Hydrogen Peroxide
Objectives:
In this experiment, the aim is to conduct the potentiometric titration of the reaction
between commercially available hydrogen peroxide and potassium permanganate.
Furthermore, to measure the potential change of the reaction. Finally, is to determine
the concentration of the hydrogen peroxide solution.
INTRODUCTION:
Hydrogen peroxide us topical antiseptic commonly used to treat cuts and wounds to
prevent infection. However, hydrogen peroxide is relatively unstable and
decomposes to form water and oxygen gas:
H
2
O
2
(aq) →H
2
O(l) + O
2
(g)
In daily life, the percentage is probably not exact 3%. One method of determine
the concentration of a hydrogen peroxide, H
2
O
2
, which is by titration with a
solution of potassium permanganate, KMnO
4
, of known concentration.
The reaction is oxidation-reduction and proceeds as shown below, in net ionic
form.
5 H
2
O
2
(aq) + 2MnO
4
–
(aq) + 6H
+
(aq) → 5O
2
(g) + 2Mn
2+
(aq) + 8H
2
O (l)
In this experiment, an ORP (Oxidation-Reduction Potential) Sensor used to
measure the potential of the reaction. The ORP sensor is based on Standard
Hydrogen Electrode (SHE) as a reference. It can detect pH, temperature and
potential of the solution. The data will look like an acid-base titration curve. The
volume of KMnO
4
titrant used at the equivalence point will be used to determine
the concentration of the H
2
O
2
solution.
Experimental procedure:
1.
An acidified and diluted hydrogen peroxide, H
2
O
2
, is prepared as solution for
the titration
a)
100mL of 0.3% H
2
O
2
from stock solution of 3% H
2
O
2
is prepared.
b)
10mL of the diluted H
2
O
2
solution is measured out precisely into a
250mL beaker. 25mL of distilled water and 10 mL of 4.5 M sulfuric
acid, H
2
SO
4
, solution is mixed carefully. CAUTION:
H
2
SO
4
is a
strong acid and should be handled with care.
