In volumetric analysis of Class 11 and Class 12, a solution of known concentration, called a standard solution, is used to determine the concentration of a second solution, called an unknown solution. This method is based on the principle that the volume of a solution required to react with a given volume of another solution is proportional to the concentration of the reacting solution.
There are several types of volumetric analysis, including acid-base titrations, redox titrations, and complexometric titrations. In each of these methods, the reaction between the standard and unknown solutions is carefully monitored using a visual indicator or an instrumental technique such as pH measurement or potentiometry. The point at which the reaction is complete, called the endpoint, is determined by the change in the indicator or the instrumental measurement.
To perform a volumetric analysis, the following steps are generally followed:
Prepare a standard solution of known concentration.
Prepare the unknown solution to be analyzed.
Set up the apparatus for the titration, including a burette to dispense the standard solution and a flask or beaker to hold the unknown solution.
Add the indicator to the unknown solution.
Slowly add the standard solution to the unknown solution while stirring, until the endpoint is reached as indicated by the change in the indicator.
Record the volume of standard solution used.
Calculate the concentration of the unknown solution using the volume of standard solution used and the known concentration of the standard solution.
Volumetric analysis is a commonly used method in analytical chemistry for determining the concentration of a substance in a solution. It is accurate, precise, and relatively easy to perform.
In volumetric analysis, several important numerical quantities are used to calculate the concentration of the unknown solution. These include:
Molarity (M): Molarity is a unit of concentration that is defined as the number of moles of solute per liter of solution. Molarity is commonly used in volumetric analysis because it is easy to calculate using the volume and concentration of the standard solution.
Titrant volume (Vt): Titrant volume is the volume of the standard solution used in the titration. It is measured using a burette or a micropipette.
Equivalent volume (Ve): Equivalent volume is the volume of the standard solution required to react completely with the unknown solution. It is calculated using the stoichiometry of the reaction between the standard and unknown solutions.
Normality (N): Normality is a unit of concentration that is defined as the number of equivalents of solute per liter of solution. Normality is used when the reaction between the standard and unknown solutions involves a transfer of electrons or ions, rather than a transfer of molecules.
Molar mass (MM): Molar mass is the mass of a substance in grams per mole. It is used to calculate the number of moles of solute in the standard solution, based on its mass and concentration.
By using these numerical quantities and applying appropriate calculations, it is possible to determine the concentration of the unknown solution in volumetric analysis.
The standard solution is a solution of known concentration that is used to determine the concentration of an unknown solution. The standard solution is typically prepared by accurately weighing out a precise amount of a pure solid chemical or by accurately diluting a concentrated solution to a known volume.
The secondary solution is the solution that is being analyzed in the volumetric analysis. It is also called the unknown solution because its concentration is not known before the titration. The concentration of the secondary solution is determined by reacting it with the standard solution in a carefully controlled experiment, called a titration.
In a titration, a small volume of the standard solution is added to the secondary solution until the reaction between the two solutions is complete, as indicated by a change in a visual indicator or an instrumental measurement. The volume of standard solution used in the titration is used to calculate the concentration of the secondary solution using appropriate formulas.
Volumetric analysis is a commonly used method in analytical chemistry for determining the concentration of a substance in a solution. It is accurate, precise, and relatively easy to perform.
Commonly used to calculate the concentration of the unknown solution:
Molarity (M) of the unknown solution: M = (Vt * Cs) / Vw
In this formula, M is the molarity of the unknown solution, Vt is the volume of the standard solution used in the titration, Cs is the concentration of the standard solution, and Vw is the volume of the unknown solution.
Normality (N) of the unknown solution: N = (Vt * Cs) / Ve
In this formula, N is the normality of the unknown solution, Vt is the volume of the standard solution used in the titration, Cs is the concentration of the standard solution, and Ve is the equivalent volume of the standard solution.
Molar mass (MM) of the unknown solution: MM = (Vt * MM of the standard) / Vw
In this formula, MM is the molar mass of the unknown solution, Vt is the volume of the standard solution used in the titration, MM of the standard is the molar mass of the standard solution, and Vw is the volume of the unknown solution.