# Freezing point lowering for a mixture of many liquids

I have been taught that if I have a solute of molality $$m$$ mixed with a liquid, the freezing point in lowered by an amount $$K_\mathrm{f}\cdot m$$ where $$K_\mathrm{f}$$ is the molal freezing depression constant.

But if I have a solution containing three liquids, and if all the $$K_\mathrm{f}$$ values are known, what would be the lowering of freezing point of such a solution?

• At some point one of the liquids will reach its own freezing point lowered by presence of two other liquids and whatever else you have there. Then it will freeze. – Ivan Neretin Mar 26 '19 at 13:31
• How do we calculate the freezing point? – Vaishakh Sreekanth Menon Mar 26 '19 at 13:42
• Precisely as you described, via molality and Kf. – Ivan Neretin Mar 26 '19 at 13:44
• Sounds about right. – Ivan Neretin Mar 26 '19 at 14:08
• It is, not surprisingly, more complicated than that. The Kf*m model is an approximation to begin with, since it presume that Kf does not depend on concentration which is a poor approximation for many real liquids. But, an extension to a ternary would seem quite possible (and ternary interaction terms are not always needed). Depends on the liquids. – Jon Custer Mar 26 '19 at 14:13