An After-Dinner Trick

In this Activity, students investigate a classic chemistry demonstration that uses the phenomenon of freezing-point depression to lift an ice cube out of a glass of water with a thread. They first test how adding salt, pepper, cream, and sugar to cold water affects the temperature. They then use the information gathered to design a procedure to lift the ice cube using any of the four substances. Use of this Activity could accompany discussion on changes of states, especially freezing and melting. It could also be used during a unit on solutions chemistry and colligative properties. The Activity could be extended to a quantitative use of the freezing-point depression equation.