Final answer:
The process of making homemade ice cream involves using a saltwater mixture to lower the freezing point of the ice cream mixture, enabling it to freeze effectively. This is explained by the colligative property of freezing point depression.
Step-by-step explanation:
When homemade ice cream is being made, a mixture that can achieve temperatures lower than -3°C is required for the freezing process. To accomplish this, salt (NaCl) is added to ice, which causes the freezing point of water to lower, allowing the mixture to freeze. This is because the salt disrupts the formation of ice crystals, lowering the solution's overall freezing point. The question asks for the freezing point of a solution made by dissolving one part salt to eleven parts water by mass. When NaCl is dissolved in water, it dissociates into its ions, which causes the freezing point of the water to decrease.
The phenomenon at play here involves colligative properties, specifically, freezing point depression, which is the process where the solute in a solvent causes a lowering of the freezing point of the solution. In an ideal solution, the freezing point depression is directly proportional to the mole fraction of the solute. This principle is what allows for the saltwater mixture to freeze the ice cream mixture inside the ice cream maker more effectively than just using ice alone.