Cryoscopic constant
In thermodynamics, the cryoscopic constant, Kf, relates the molality of a solution to its freezing point depression (which is a colligative property). It is the ratio of the latter to the former: Δ T f = i K f b {\displaystyle \Delta T_{\mathrm {f} }=iK_{\mathrm {f} }b} Δ T f {\displaystyle \Delta T_{\mathrm {f} }} is the depression of freezing point, calculated as the freezing point T f 0 {\displaystyle T_{\mathrm {f} }^{0}} of the pure solvent minus the freezing point T f {\displaystyle T_{\mathrm {f} }} of the solution; i is the van ‘t Hoff factor, representing the number of particles the solute dissociates into or forms when dissolved; b is the molality of the solution (moles of solute per kilogram of solvent).