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Molality
As with Solubility, Molality (m) is a way to represent amounts of solute and solvent in a solution. Unlike Solubility, however, molarity (and molality) deal with any solution, it does not have to be a saturated solution like Solubility. Here, the big issue is that molality deals with the kilograms of solvent and the moles of solute. So the difference between Molarity and Molality is that the denominator is volume of solution and kilograms of solvent, repsectively. The equation is:
M = moles of solute / kgsolvent written like this:
So again, Molality problems are simply ratio of fraction set equal to each other where one ratio you have all the information (known ratio) and the second ratio where you are missing information. When you are determining the amount of solvent or solute needed to create a given molality (m) solution, you will need to show the units of m as its component (mole solute chemical formula / 1 kgsolvent) so that you are showing units canceling.