Volumetric analysis, also known as titrimetric analysis is one of the quantitative means of chemical analysis that involves the measurement of the volume of a solution of known concentration which is required to react with the analyte.
A titrimetric method of analysis is based on a chemical reaction such as:
where n molecules of the reagent, Y, and m molecules of the analyte, X, react. The reagent Y in solution is called standard solution and its concentration is determined by the process of standardization. Until an amount of Y that is chemically comparable to that of X has been added, the titrant is continued to be added. The equivalence point is then said to have been reached. An indicator that shows the excess of titrant by changing color can be used to determine when to stop adding titrant. The endpoint of the titration is a point at which the color of the indicator changes. The endpoint should be as near to the equivalence point as possible.
Requirements of Titrimetric Analysis
The reaction involved in titration must fulfill the following requirements:
- The chemical reaction must be simple. The reagent and the substance to be determined should completely react in stoichiometric proportion.
- Only one specific reaction should occur between the titrand (analyte) and titrant. There should be no side reaction.
- The reaction involving titrant (reagent of known concentration) and titrand (solution being titrated) should be relatively fast. If needed, the catalyst may be used to increase the speed of reaction.
- The exact concentration of titrant must be known.
- Some physical and chemical properties of the solution must change at the endpoint.
- The end-point of the titration should be clearly distinguishable using an indicator.
- The equivalence point and the end point should almost coincide with each other.
- An indicator should sharply define the reaction’s endpoint by changing physical or chemical properties.
Types of Titrimetric Analysis
- Neutralization or Acid Base Titration: Involves neutralization reaction in which acid is treated with an equivalent amount of base or vice-versa.
- Redox (Oxidation-Reduction)Titration: Involves estimation of an oxidizing agent with the help of a standard solution of a reducing agent or vice-versa.
- Complexometric Titration: Involves the formation of a complex between the analyte (metal ions) and the titrant (ligand).
- Precipitation Titration: Involves the formation of an insoluble precipitate when two solutions are brought together.
Advantages of Volumetric Analysis
- It is a rapid method.
- Gives precise and accurate results when done carefully.
- It is carried out using simple apparatus.
- It costs cheap in comparison to other analytical methods.
- It can be used with many other techniques like visual titrimetry, voltammetry, conductometry, and so on.
- It has a wide range, which allows for the estimation of various analyte types, including complexing species of acids, bases, oxidants, and reductants.
Application of Titrimetric Analysis
Some of the major applications of volumetric analysis are:
- In the determination of hardness of water.
- To determine total iron content in water.
- Estimation of ferrous and ferric ions in a given mixture by potassium dichromate solution.
- Determination of ‘Available chlorine’ in bleaching powder.
- Determination of the amount of NaCl and KCl in a given mixture by AgNo3.
- Used to determine magnesium and manganese content in a solution by using EDTA.
Errors in Volumetric analysis and Precautions
Errors in volumetric analysis arise due to the following reasons:
- Use of non-homogeneous solution.
- Inaccuracy of instrument used
- Errors in weighing
- Impurity of materials
To avoid such errors, the following precaution must be taken to get accurate results in volumetric analysis:
- The apparatus required for the titration should be well-cleaned with chromic acid and then washed with distilled water. The measuring flask, burette, and pipette should all be calibrated against standard equipment.
- The solutions for the titration should be prepared using distilled water.
- The chemical must be precisely weighed using a digital weighing machine before being used to prepare the standard solution.
- Burette reading should be noted correctly by adjusting the eye level.
- Titration should be carried out with patience in the sense that the solution from the burette should not be delivered continuously, rather it should be delivered drop by drop.
Difference between gravimetric and volumetric analysis
Gravimetric analysis is a quantitative approach in analytical chemistry that is based on determining the quantity of analyte based on the mass of the solid. It involves chemical reactions that lead the desired substances to precipitate. The results are obtained in grams.
Volumetric analysis is the quantitative method of chemical analysis that involves the measurement of the volume of a solution of known concentration which is required to react with the analyte. In other words, it is means of determination of the amount of analyte based on its volume. Such analysis involves chemical processes that have the ability to alter the color of the sample. The results are obtained in milliliters.
Titrimetric Analysis Video
Titration is a quantitative chemical analysis in which the concentration of a solution is determined by using another solution with a known concentration.
Standard solution refers to the solution of reagent of known concentration that is used in volumetric analysis.
The point at which indicator changes color and indicates the completion of the reaction is called the end-point of the titration
The point in a titration at which the amount of added titrant becomes chemically equivalent to the amount of analyte in the sample.
What is volumetric analysis?
Volumetric analysis is a quantitative method of determination of the amount of analyte based on its volume.