Question

Differentiate between molarity and molality of a solution. How can we change the molality value of a solution into molarity value?

Answer 1

Molarity	Molality
1. The number of moles of solute present in per liter of solution.	1. The number of moles of solute present in $1kg$ of solvent.
2. It depends on volume.	2. It depends on mass.
3. Volume changes with temperature, hence it is temperature dependent.	3. It depends on mass which is independent of temperature.

To convert Molality value into Molarity value, we have to use the following formula:-

$m=\frac{1000\times M}{1000\times (d-M)\times M_b}$

or, $M=\frac{d}{(m\times M_b)+1}$

where, $M$: molarity, $m$: molality, $d$: density, $M_b$: Molecular mass.