CALCULATIONS INVOLVING COLLIGATIVE PROPERTIES. Section 18.4. AFTER READING SECTION 18.4, YOU SHOULD KNOW:. How to calculate molality (m) How to calculate the molar mass of a molecular compound from the freezing point depression or boiling point elevation. MOLALITY .
nA = moles of solute A nB moles of solvent B
nA + nB nA + nB