Introduction of Molarity:
The natures of solvent as well as of solute are not the only criteria that should be considered to have an idea about the behaviors and properties of most of the substances in solution form. Rather there is very important role of concentration of solute in a solution.
Although there are so many units that are available in varied literatures that are used to express concentration of any solution. But among them, the most commonly used one is Molarity.
Molarity is defined as a ration of number of moles of solute that are dissolved in unit volume i.e. per liter of the solution.
Molarity is denoted by the symbol “M”.
Molarity can be formulated as,
Molarity= number of moles of solute / volume of solution in liter on dm3.
So it is very obvious from the formula that the number of moles of solute as well as total volume of solution must be known for the calculation of Molarity.
In SI system, the unit of Molarity is mol/m3. But the unit in general practice is mol/L or 1 mol/dm3.
A solution whose concentration is 1 1 mol/L is said to be a molar solution.
Difference between Moles & Molarity:
Mole just tells that how much quantity or amount is present of a material while molarity tells us about the concentration of that material.
Characteristic of reliance on volume:
Molarity depends upon the volume of a solution. The reason behind it is that it mainly happens because of the thermal expansion.
Although concentration is expressed in many different units, nut the most commonly employed is molarity or molar concentration. Its analytical applications are very much wide because calculations related to stoichiometry are become much easier. Along with that, Molarity measures the concentration with great precision and accuracy.
The mere disadvantage of Molarity is that as this concentration expression depends on thermal expansion, so whenever a solution is subjected to heat, it gets warmer. As a result of it, in most of the instances, Molarity value falls and we get an artifact result.
Methods of Molarity Calculation:
Two methods are available which are as following. Choose the method which is more appropriate with your skills and easiness to calculate molarity.
This method involves Molarity calculation steps 1 by 1.
- Find out the number of moles of solute dissolved in a solution.
- Find out the volume of solution in liters.
- Divide number of moles of solute by volume of solution in liters.
Here, the calculations of molarity can be done all together in a single step.
- Divide number of moles of solute by volume of solution in liters. (No matter whatever the units are)
- Convert the amount of solute dissolved in the solution into number of moles of solute by means of using dimensional analysis.
- Convert the volume of the solution into liters of solution by means of using dimensional analysis.