Students should be asked to describe results from the product evaluation stage of the technological design process. Physical Science Standards Properties and Changes of Properties in Matter, Grades 5-8 A characteristic property of stearic acid soaps is they are less soluble in water than other soaps due to the structure of stearic acid. Another characteristic property of these soaps is a low density from a large number of trapped air bubbles, which causes the soap bar to float. A characteristic property of oleic acid is a low melting point which causes oleic acid soaps to be liquid at room temperature. A characteristic property of coconut fatty acid soaps is solubility in water and a low melting point.
Substances have different characteristic properties.
The types of substances included in a mixture play an important role in determining the properties of the final mixture. Substances react chemically in characteristic ways with other substances to form new substances with different characteristic properties. When sodium hydroxide reacts with a fatty acid, it produces soaps, which are salts of fatty acids, and glycerol. Transfer of Energy, Grades 5-8 Heat moves in predictable ways, flowing from warmer objects to cooler ones. While not the main point of this activity, students do witness the phenomenon when the lard melts from the heat of the burner or hot plate.