Students should be familiar with solids, liquids, and gases (TEKS 3.5B). Solids keep their shape and have a definite volume. Examples include books, chairs, and cups. Liquids take the shape of their container and also have a definite volume. Examples include milk, water, and juice. Gases take the shape of their container, and their volume expands to fill it. Examples include air, oxygen, and helium.
Refer to solids, liquids, and gases as states of matter or physical states to familiarize students with alternate terminology. These phrases are synonyms for solids, liquids, and gases.
Notebooks are required tools for students (TEKS 3.4A) and help them record, organize, and process their work. Students can use their notebooks as study guides, too.
Provide students time to think and discuss the answers to the questions regarding what happens to chocolate when it gets warm and what to do to make it less messy. Some students may have prior knowledge with melted chocolate in a car on a hot day. The chocolate becomes messy because it changes from a solid to a liquid with the addition of heat.
In order to make it less messy, the chocolate could be placed in a freezer to solidify it again.
Download and print Explore: Part 1 for each student. Click on Related Items, and look under Related Documents to locate this recording sheet.
When heat was added to solid chocolate, the temperature increased, changing the chocolate to a liquid. The liquid chocolate took the shape of its container. By pushing the “Test” button, the tongs reached out and shook the container. This caused the liquid to move or slosh around the container.
When students pushed the “Cool” button, the liquid chocolate changed back to a solid. The melted chocolate took the shape of the container and the chocolate retained that shape when it solidified, so the only way for students to know a change in state occurred was to push the “Test” button again. The tongs reached out and shook the container, but this time the solid chocolate did not move like it did when it was a liquid.
Ask students to predict what they think will happen with the other materials.
Distribute Explore: Part 1 to each student. Ask students to record their observations as they work through the activities for candle wax, aluminum can, and butter.
Download and print Explore: Part 2 for each student. Click on Related Items and look under Related Documents to locate this recording sheet.
When ice is heated, it melts into water. A solid changes to a liquid when heated to a certain temperature.
When water is cooled to 0 ℃, it freezes into ice. A liquid changes to a solid when cooled to a certain temperature.
When water is heated to 100 ℃, it boils and changes into vapor. A liquid changes to a gas when heated to a certain temperature.
When vapor is cooled below 100 ℃, it condenses into water. A gas changes to a liquid when cooled to a certain temperature.
If vapor is heated above 100 ℃ in a closed system, the particles will expand enough to blow the lid off the system to release pressure.
Instruct students to click on the animation to fill in the flow chart. They will drag the state of matter words to the appropriate boxes. “Gas” belongs in the far left box, “liquid” belongs in the middle, and “solid” goes on the far right. Upon completion, students should copy the flow chart into their notebooks.
When heat is added to ice, it melts to water. When heat is added to water, it changes to water vapor at 100 ℃.
When water vapor is cooled, it condenses and changes into water. When water is cooled to 0 ℃, it changes to ice.
Gold jewelry and gold scraps can be melted into gold bars at an extremely high temperature. The melting point of gold is 1064 ℃ (as compared to 100 ℃ for water). After the gold jewelry is melted from a solid to a liquid, it can be poured into a mold and allowed to cool. Once sufficiently cool, the gold bar changes from a liquid back to a solid and can be removed from the mold.
Gold jewelry is made the same way. Gold is heated at an extremely high temperature, melted into a liquid, poured into a mold, cooled back into a solid, and extracted from the mold.
Without the use of heating and cooling, we could not repurpose unused gold or create new gold jewelry.
The quiz has five questions. Students will have three chances to correctly answer a question before the next question is introduced. Each question provides the student with immediate feedback. Following the completion of the quiz, students may review the quiz to view correct and incorrect answers.
1. “Gas” belongs in the blue box farthest to the left, followed by “liquid” in the middle, and “solid” on the far right.
2. Evaporation occurs, heat is added, and a liquid changes to a gas when water boils.
3. The statement is true.
4. Melting is what occurs when a solid changes to a liquid with the addition of heat.
5. A crayon melting in a hot car is an example of a solid changing to a liquid.