Up close and freezing: Chemistry in Pictures Winner

Jack Glaser, a student in Jenn Wagner’s class at Scarsdale High School, Scarsdale, New York submitted this amazing photo of an aqueous solution freezing. When the temperature of water decreases towards the freezing point, the solubility of the gases in the medium decreases, resulting in the gases being "pushed" out of the liquid phase. Since water freezes from the outside, this results in the formation of a series of pockets of air that are not only visually distinctive as demonstrated in this photo, but also affect the strength and color of the ice formed. In this case, students were invited to observe this effect during the course of an experiment comparing the freezing points of aqueous solutions with different quantities and types of solutes.