A mass of 0.630 g of nacl is dissolved in 525 g of water. part a calculate the molality of the salt solution.

Molality is simply defined as the number of moles of solute over the mass of the solvent.

In this case the solute is NaCl and the solvent is water, therefore:

moles solute = 0.630g / 58.44 g/mol = 0.0108 mol

So the molality is:

m = 0.0108 mol / (0.525 kg)

m = 0.0205 molal