The Effects of Temperature on Physical and Chemical Changes SC.5.P.9.1 . Today, we are going to talk about the three physical changes of matter. You may already know that common materials like water, for example, can be changed from one state to another by heating and cooling. The student knows that common materials (e.g. water) can be changed from one state to another by heating and cooling.

Physical Change A physical change takes place when a substance changes in size, shape or form. Many times a physical change is due to a change in temperature. A physical change takes place when a substance changes in size, shape, or form. However, the particles do not change. Examples of physical changes are chopping vegetables, drying clothes, or cutting paper. In each of these cases, the original substance is just altered, not changed completely. Physical changes are often times due to a change in temperature of the substance. Melting Butter Temperature Changes Drying Clothes

Melting Evaporation Melting occurs when a solid changes into a liquid. Key Word(s): Increase in Temperature, Heat, Warm Evaporation Evaporation occurs when a liquid changes into a gas. Melting is a physical process that results in an increase in temperature change causing a substance to turn from a solid to a liquid. Melting gold and reforming it into a piece of jewelry, unlike the original piece, is an example of a physical change because the gold substance itself has not been altered. When ice-cream is melted, it turns back into a liquid. Words that signify melting are an increase in temperature, heating, and warming. Evaporation occurs when a liquid changes into a gas. The key word that signals the process of evaporation is the word boiling. Water is a very useful example. If you boil a pot of water on the stove and forget about it, all the water will eventually evaporate into the air. Key Word(s): Boiling

Condensation Freezing Condensation occurs when a gas changes into a liquid Key Word(s): Dew, Fog, Humidity Freezing Condensation is the process of changing a gas into a liquid. The key words here are dew, fog, and humidity. If you wake up early in the morning, you might see little drops of water on the grass or on plants. We call this dew and it occurs when air, which contains water vapor, cools. This vapor then condenses to form small water droplets. Freezing is a process by which changes in temperature result in a liquid changing into a solid. Take water for instance, we can make ice cubes by freezing water in a small tray. Key words associated with freezing are: ice, cold, snow, and decrease in temperature. Freezing occurs when a liquid changes into a solid Key Word(s): Ice, Cold, Snow, Decrease in Temperature

Chemical Change A chemical change takes place when a substance is completely altered. A chemical change, on the other hand, takes place when a substance is completely altered. In a chemical change, the particles of matter do change. Some examples of a chemical change are a rusting car, burning wood, and rotting food. These changes are not reversible. Rusted Car Rotten Food Burned Wood

Chemical Change Burning Rusting There are a few terms that are associated with chemical changes: burning and rusting as seen in the pictures.

Chemical Change Chemical Reactions Rotting Rotting and other chemical reactions are other key words that indicate that a chemical reaction is taking place.

Physical and Chemical Changes A change that takes place when a substance changes in size, shape or form. The particles of matter do not change. A chemical change takes place when a substance is completely altered. The particles of matter do change. Adding dirt to a puddle Adding salt to water Sun burned skin Car Burning Gas Burning Wood Sawing Wood Baking a pie Physical Change Chemical Change A change that takes place when a substance changes in size, shape or form. The particles of matter do not change. A change that takes place when a substance is completely altered. The particles of matter do change. Sun burned skin Burning Wood Adding salt to water Let’s complete one last activity. I’m going to show you a picture and I want you to raise your hand to tell me whether it is a physical change or a chemical change. (Go through each picture and wait for student responses.) Excellent work! Remember, a substance that goes through a physical change will change only in size, shape, or form; but, a substance that goes through a chemical change, will be altered completely. Clothes Dryer Adding dirt to a puddle Car Burning Gas Baking a pie