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It’s Just a Phase: Heating and Cooling Curves—ChemTopic™ Lab Activity

firewatch

When freezing weather is predicted, Florida’s orange growers spray their trees with water to prevent the fruit from freezing. When water freezes, it releases heat to its surroundings and protects the fruit from damage. The temperature of the freezing water mixture will remain at the freezing point as long as both ice and water are present. With the It’s Just a Phase: Heating and Cooling Curves—ChemTopic™ Lab Activity, investigate the solid–liquid phase changes for lauric acid, an organic compound used to make soap. Temperature versus time data are measured as the melted solid is slowly cooled and again as the solid is reheated. Analyze the resulting heating and cooling curves to determine whether the freezing point/melting point depends on the direction of the physical change.

Concepts

  • Solids and Liquids
  • Melting Point
  • Phase Changes
  • Kinetic-Molecular Theory