Question

Will the molarity of a solution at \[{50^0}{\text{C}}\] be same, less or more than molarity at \[{25^0}{\text{C}}\] ?

Answer 1

Hint: Molarity of a solution is defined as the number of moles of any substance present in one litre of a solvent. Mathematically,
Formula used:
${\text{Molarity = }}\dfrac{{{\text{No}}{\text{. of moles of the solute}}}}{{1{\text{litre of the solution}}}}$
$ \Rightarrow {\text{molarity = }}\dfrac{{{\text{mass of the solute}}}}{{{\text{molecular weight of the solute}}}} \times \dfrac{{1000}}{{{\text{volume of the solution}}}}$

Complete step by step answer:
From the formula it can be seen that the molarity of a solution is dependent on the volume of the solution and it bears an inverse relation to the volume. That means, when the volume of the solution is large then the molarity is low and for a small volume, the molarity should be high, for a fixed mass of the solute.
Now, the volume of any solvent or any solution is dependent on the temperature of the medium and is directly proportional to the same. That means if the temperature of a solution is increased then the volume increases and if the temperature falls then volume also decreases.
Accordingly, the molarity of the solution should be inversely proportional to the temperature of the solution. As the temperature increases the molarity should decrease and as the temperature increases the molarity should decrease.

Note:
The molality of the solution which is the number of moles present per Kg of the solvent on the other hand is not affected by the temperature of the medium because the solvent is expressed in units of mass which is a fixed quantity, not affected by the temperature of the medium. So, molality is a better way to express the concentration of a medium.