Different types of redox titratiions for B.Pharm 1st sem. as per the PCI syllabus

1. Types of Redox Titration Principles and Applications
Redox titration refers to a laboratory method to determine the analyte
concentration by carrying out a redox reaction between the analyte
and the titrant. The redox titration often needs a redox indicator or a
potentiometer.
Rodex titration depends on an oxidation-reduction reaction that
occurs between the analyte and the titrant. It is also one of the most
common methods for identifying the concentration of the analytes
that are unknown.
For evaluating the redox titrations, it is essential to obtain the shape of
the titration curve that corresponds. In a redox titration, it is much
convenient for monitoring the concentration of the reaction potential
instead of that of the reacting species.
Principle of Redox Titration
Let us discuss the theory of redox titration.
Redox reactions consist of both oxidation and reduction reactions. The
primary features of these reactions are as follows:

2. Reduction Reaction
A substance undergoes a reduction in the following ways:
1. Addition of hydrogen atom
2. Removal of the oxygen atom
3. Accepting electrons
4. Reduction in the oxidation state of the substance
Oxidation Reaction
A substance undergoes oxidation in the following ways:
1. Addition of oxygen
2. Removal of hydrogen
3. Loss or donation of electrons
4. An overall increase in the oxidation state of the substance
5. Hence, we can say that redox titrations consist of a transfer of
electrons between the titrant and the analyte. An example of this
type of a redox reaction is reacting the iodine solution with a
reducing agent. A starch indicator is used to determine the
endpoint of this redox titration. Here, the diatomic iodine gets
reduced to the iodine ions and blue coloured iodine solution
loses its colour. This reaction is known as iodometric titration.

3. Redox Titration Examples
The titration of potassium permanganate against oxalic acid is a great
example of redox titration. The reaction is explained below.
Titration of Potassium Permanganate Against Oxalic Acid
1. Firstly prepare a standard oxalic acid solution, roughly 250 ml.
2. The molecular weight of oxalic acid can be calculated when the
atomic weight of all the atoms is added. Doing so, we get the
molecular mass of oxalic acid, which is,
3. As the weight of the required oxalic acid for making 1000ml of
1M solution is found to be 126g, the weight of the same for
making 250ml of 0.1M solution is,
126/1000 х 250 х 0.1 = 3.15g
Redox Titration Indicators
There are three different types of indicators that are required for
signalling the endpoint of redox titration. The oxidised and reduced
forms of titrants like MnO⁻₄ possesses different colours. The MnO⁻₄
the solution is a strong purple colour, however, when it is used as a
titrant, the mixture tends to remain colourless till the equivalence
point is reached. The endpoint is indicated by the very first drop of the
excessive MnO⁻₄ which gives the solution a permanent purple colour.

4. Amongst the most vital class of indicators, lie these materials which do
have a contribution in the redox titration, however, their oxidised and
reduced forms are different in colour. When a redox indicator is added
to the titrant, the colour imparted by the indicator is dependent on the
potential of the solution. Since the potential of the mixture tends to
change when the titrant is added, the indicator changes the oxidation
state and the colour, which indicates the endpoint of the titration.
FAQ’s
1. Give the Redox Titration Definition.
The redox titration is a type of titration which is based on a redox
reaction between the analyte and the titrant. It also involves the use of
a potentiometer or a redox indicator. An example of this type of
titration is treating an iodine solution with a reducing agent. This
would result in creating iodide with the help of a starch indicator to
determine the endpoint. Iodine, I2, is reduced to iodide, I-in this redox
titration. When all the amount of iodine is consumed in the reaction,
the purple colour of iodine vanishes. This is referred to as an
iodometric titration

5. What is the Indicator Used in Redox Titration?
Ans: A redox indicator also referred to as an oxidation-reduction
indicator, is a type of an indicator that undergoes a specific colour
change at a particular electrode potential. The requirement for a
reversible and faster change in colour, the oxidation-reduction
equilibrium for an indicator redox reaction has to be achieved very
fast. Hence, only some classes of the redox systems are used as
indicators.
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