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




Molarity of a given solution is defined as the total number of moles of solute per litre of solution.

Molality is defined as the total moles of a solute contained in a kilogram of a solvent.

Mathematical expression is M = number of moles of the solute /Volume of solution given in terms of litres.

Mathematical expression is

m = Numbers of moles of solute/Mass of solvent in kgs

m = (g ✕ 1000)/(W ✕ m).

Depends on volume of the whole solution.

Depends on the mass of the solvent.

Unit sign expressed as (M).

Unit sign expressed as (m).

Molarity has a unit of moles/liter.

Molality has units of moles/kg.

The relationship between the molarity (M) and molality (m) is expressed as below.

\(m= frac{1000times M}{1000times (d-M)times M^{‘}}\)

M = Molarity.

m= Molality.

M’ = Molar mass of the solute.

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