1. Why was molality used as opposed to molarity? Mass of solvent is more consistent at temperature extremes, as volume can fluctuate due to temperature changes. Since molarity is moles solute per liter of solution, we cannot use molarity as our concentration unit. Therefore, we use molality (moles solute per kg of solvent) since the kg of solvent doesn't change with temperature. 2. Why can supercooling of a liquid occur? Explain why the temperature increases as the solution freezes. Supercooling of a liquid can occur due to the lack of a seed crystal or nucleus around which a structure can begin forming to create a solid. Thus, the liquid phase can be maintained beyond the normal freezing point of a liquid. For example, salt lowers the vapour pressure of water, thus lowering its freezing point and allowing supercooling to occur. The temperature of the solution seemingly increases as the solution freezes due to it being supercooled/cooled beyond normal freezing point. Freezing is an exothermic process, that is, it must give of energy/remove heat or the freezing process will stop.