how is

m= w2/m2 // w1/1000


how did it come?

Dear Student,

The correct expression of molality is [(w2 / M2.) / w1 ] x 1000

m is known as molality of solute. It is defined as number of moles of solute in 1 kg of solvent.

Let us suppose that w2 g of solute with M2 g/mol of molar mass is dissolved in w1 g, of solvent.

Number of moles of solute = w2 / M2.

Thus, Molality, m = (w2 / M2.) / w1 in grams.

Since molality is moles/kg, therefore, we need to convert mass of solvent from g to kg.

So, m = [(w2 / M2.) / w1 in kg] x 1000

Hope its clear now.

Enjoy learning!!

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