Physical Properties 4.7 A The student knows that matter has physical properties. The student is expected to observe and record changes in the states of matter caused by the addition or reduction of heat.

States of Matter There are three states of matter:  solid  liquid  gas

Changes can happen! Matter can undergo changes. What are some ways in which a solid might be changed? Broken into pieces (pressure) Melted (temperature) Melted (temperature)

More Changes In what ways might a liquid be changed? Decreased temperature (freeze) Increased temperature (boil) Evaporation

Even more changes This is a hard one! Put your thinking caps on tight! In what ways might a gas be changed? An example: The gas (air) condenses on a glass of cold water and forms a liquid on the outside of the glass. Know that: Gases can be changed by an increase in temperature or a decrease in temperature.

What is happening? STARTS CHANGES TO WHAT HAPPENED? SolidLiquid Temperature increased LiquidGas LiquidSolid Temperature decreased GasLiquid

Common temperature changes Boiling: Boiling: water 100°C water 100°C Freezing: Freezing: water 0°C water 0°C

To Help Us Remember When it’s zero it is freezing When it’s 10° it is not When it’s 20° it is warm When it’s 30° it is hot

A student places a beaker of water on a hotplate. What will happen to the water in the beaker when the heat is added? A.The water will change from a solid to a liquid. B.The water will change from a liquid to a solid. C.The water will change from a liquid to a gas. D.The water will change from a gas to a solid.

Answer: C The water will change from a liquid to a gas.  A is incorrect because water is a liquid and did not begin as a solid.  B is incorrect because it will not turn into a solid because of the addition of heat instead of the reduction of heat  C is correct because water is a liquid and when the heat is added to it water vapor is formed which is a gas.  D is incorrect because water is a liquid and did not begin as a gas.

A group of students observe an ice cube as it sits on their lab table. As the ice cube begins to change, the students discuss what is happening. What is the best explanation for the change in the ice cube? A.The ice cube is warmer than the air around it. B.The temperature of the table increased. C.The ice cube is warmer than the table. D.The ice cubes temperature increased.

Answer: D Answer: D The ice cubes temperature increased.  A is incorrect because the ice cube is not warmer than the temperature in the classroom  B is incorrect because the temperature of the table is not increasing.  C is incorrect because the ice is 0°C and is NOT warmer than the table (room temperature)  D is correct because the temperature of the ice cube is increasing because of the warmer air around it and from the heat transfer from the table.

A candy maker was making chocolate mint wafers. She stirred all the ingredients in a pan on the stove to make the chocolate mixture. Next, she poured the liquid into small molds and allowed the chocolate to sit for 3 hours on her countertop. The mints were then able to be taken from the molds with her fingers. Why was the chocolate mixture no longer a liquid?

A. The chocolate evaporated. B. The chocolate needed to be stirred in the mold. C. The chocolate cooled off and became a solid. D. The chocolate separated into little pieces.

 A is incorrect because the chocolate was in the molds. If it had evaporated it would not be present.  B is incorrect because stirring the chocolate would not keep it as a liquid but only help in reducing the temperature and cooling it off.  C is correct because the chocolate cooled off and because of the decrease in temperature became a solid.  D is incorrect. The question mentioned nothing about the candy separating into little pieces. Answer: C The chocolate cooled off and became a solid.

What about this? A class had many plants in their classroom. They used two large containers to hold the water for watering their plants. One container was left on the windowsill and the other was kept in a refrigerator. Over a two week break from school the students came back to find lower amounts of water in both jugs. The one in the windowsill had a lot less water in it then the one in the refrigerator. A class had many plants in their classroom. They used two large containers to hold the water for watering their plants. One container was left on the windowsill and the other was kept in a refrigerator. Over a two week break from school the students came back to find lower amounts of water in both jugs. The one in the windowsill had a lot less water in it then the one in the refrigerator. Answer the following questions using Answer the following questions using scientific explanations: scientific explanations:

Why were there different amounts of water in the containers after two weeks? Evaporation – being left with no lid to contain the water in the containers, the water will evaporate. The one on the windowsill will evaporate more due to the increase in temperature.

Why did the container in the refrigerator loose water? Evaporation – note that evaporation does not just happen in the sun. Think of items in the refrigerator (an open coke can, a glass of milk, etc.) that evaporated because it was left in there for a long time. It did not lose as much as the container that was on the windowsill and in the sun but still evaporated.

How could the amount of water in the containers been kept the same over the two week period? A lid on the containers would have contained the water to the jugs and would not have allowed evaporation to occur.

Sources:  All graphics are Microsoft Clipart