Karen,+Julio,+Justin,+and+Patricia

Ice cream ingredients are surrounded by a mixture of ice and salt. As salt is added to the water its particles **dissociate**, resulting in the salt compound dividing into its two **ions** (Na+ and Cl-). When salt dissolves into water, it lowers the freezing point of the water by several degrees. This **colligative property**, which describes the ability of a dissolved solute to lower the freezing point of its solution, is known as **freezing point depression**. The water, which normally freezes at zero degrees Celsius, will remain a liquid through lower temperatures. The phase change of the ice turning into water consists of an **endothermic** phase change. Heat is being absorbed during the melting process of the ice. This endothermic reaction absorbs heat allowing for the ice cream ingredients, surrounded by the salt and water solution, to decrease in temperature because of the heat transfer. Thus, allowing for the ingredients to reach lower temperatures and being to freeze.