This all-in-one online Molality Calculator performs calculations using the formula linking the molality of a solution with the amount of the solute (in moles) and the mass of the solvent.
Molality Formula
Molality is defined as the amount of solute in moles, divided by the mass of the solvent in kilograms:
The main advantage of using molality over molarity as a measure of concentration is that molality only depends on the amount of substance of solute and solvent, which are not affected by changes in temperature and pressure. In contrast, molarity is defined as the amount of substance per unit volume of solution and is likely to change as temperature and pressure change.
In many applications, this is a significant advantage because the amount of substance is often more important than its volume (e.g. in a limiting reagent problem).
Another advantage of molality is the fact that the molality of one solute in a solution is independent of the presence or absence of other solutes.
For one-solute solutions molality and molarity are related by the following formula:
where
M – molarity,
m – molality,
W – molar mass of the solute,
ρ – mass density of the solution.
Related calculators
Check out our other chemistry calculators such as Molarity Calculator or Mole Calculator.