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Saturday, August 6, 2022

Volumetric Analysis: Principle, Types, Procedure & Applications

Learn about the principle, types, procedures, and applications of the volumetric technique which is used to determine the concentration of a substance using the known volume of a known substance.

Chemical analysis is an important part of the study of different materials or substances. It is broadly classified into two forms: qualitative analysis and quantitative analysis. Qualitative chemical analysis is a branch of chemistry that that deals with the identification of elements or grouping of elements present in a sample.

Quantitative analysis is any technique used to determine the concentration of a substance in a sample. It is further divided into gravimetric analysis and volumetric analysis.

Titration, also called titrimetry, is a type of quantitative analysis that is used to determine the amount of a specific substance in an unknown given sample. Since measuring volume is the most important part of this analysis, it is also called volumetric analysis.

In the process, the titrant is added to the analyte until a certain endpoint or equivalence point is reached. The reaction's endpoint is identified using an indicator. The indicator causes the color of the solution when the endpoint is reached.


Definition of volumetric analysis:

"The process of titrating a solution to find out how much of a substance is in it, by volume"

What is volumetric analysis?

Volumetric analysis, also known as titration, is a quantitative chemical analysis technique that is used in laboratories to determine the concentration of an analyte by measuring the volume that it occupies or, more broadly, the volume of a second substance that combines with the first in known proportions, also known as titrimetric analysis.

In other words, volumetric analysis or titration refers to the process of measuring the volume of a second substance that combines with the first in known proportions. It is used in laboratories which allows us to determine the concentration of analyte. 

The titrant is a reagent that produced a standard solution with a specific volume and concentration. The titrant reacts with an analyte solution to determine the concentration of the analyte.

History of volumetric analysis:

The French chemist Jean-Baptiste-Andre Dumas derived and found the first volumetric analysis method while attempting to quantify the proportion of nitrogen with other elements in organic compounds.

To assure the conversion of the chemical into pure gas, the nitrogen compound was burned in a furnace and passed through the furnace in a stream of carbon dioxide (CO2) that is passed into a strong alkali solution. The mass of the nitrogen is calculated, which occupies the sample under conditions of pressure and volume that are already known.

Example of volumetric analysis:

Volumetric analysis refers to any method of quantitative analysis in which the quantity of a substance is determined by measuring the volume that it occupies the volume of a second substance that combines with the first substance in known proportions.

For example, acid-base titration, preparation, and standardization of sodium hydroxide (NaOH) solution.

Principle of volumetric analysis:

The following are some of the fundamentals of volumetric analysis:
  • The solution that needs to be examined must have an unknown number of chemicals.
  • To show the end-point of the reaction a chemical with an unknown amount reacts with a substance of unknown concentration in the presence of an indicator (E.g. phenolphthalein/methyl orange). The endpoint is the point at which a chemical process is complete.
  • The titration procedure, which measures the volumes, is used to complete the reaction between the titrant and titrand.
  • The amount of reagent and solution is represented by the volume and concentration of the reagent used in the titration.
  • The mole fraction of the equation determines the quantity of an unknown substance in a given volume of solution.
When the reaction reaches its endpoint, the volume of reactant consumed is measured and used to calculate the volumetric analysis of the analyte (molarity or normality) using the formula Ca= Ct Vt M / Va.

Types of volumetric analysis:

The volumetric analysis can be classified into the following three types:
  1. Simple titration
  2. Back titration
  3. Double titrations

1. Simple titration: 

A simple titration is a method of determining the concentration of an unknown solution using a solution of known concentration. The simple titration can be subdivided into the following four categories:

2. Back titration:

In a back titration, the concentration of an analyte is determined by reacting it with a known amount of excess reagent, whereas in a direct titration, the concentration of an unknown compound is examined directly. Back titration is also known as indirect titration in which excess reagents are not added.

3. Double titration:

These types of titrations are carried out to find out the percentage content of an acid or alkali mixture. Gilson's titration method is also known as double titration, which determines the concentration of organometallic compounds in hydrocarbon solvents.

In the first step, the base concentration in the solution is determined. The concentration of the metal-organic complex can be calculated in the second stage by determining the residual amount of alkali after the organometallic compound and halide react.

Procedure of volumetric analysis:

Common apparatus required to perform volumetric titration are burette, conical flask, beaker, pipette, funnel, volumetric flask, wash bottle, etc. Following are the steps used for volumetric analysis:
  1. All glassware should be cleaned and dried according to standard laboratory procedures.
  2. Remove air bubbles from the burette and adjust the reading to zero.
  3. By precisely weighing the chemicals, accurately prepare the standard solution and a sample of the material to be measured in the solution.
  4. A common titration begins with the placement of a conical flask underneath a burette, which contains the solution of analyte/sample and a few drops of suitable indicator (such as methyl orange or phenolphthalein).
  5. Then, the titrant is dropwise added to the analyte until a change in the indicator's color is observed, showing that the endpoint of the titration has been reached. This indicates that the amount of titrant present equals the amount of analyte present due to their interaction.
  6. Depending on the desired endpoint, a single drop of the titrant can cause either a temporary or permanent change in the color of the indicator.
  7. To get accurate results, repeat the titration three times, and properly record the readings of the burette. Take their mean and calculate the molarity/normality of the sample.
Volumetric Analysis: Principle, Types, Procedure & Applications

Applications of volumetric analysis:

Volumetric analysis is one of the fundamental analytical techniques in chemistry and is applied for quantitative analysis in life sciences, pharmaceuticals, clinical chemistry, cosmetic industry, water pollution, wastewater management, food industry, wine industry, etc.


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