Unit 13 Lesson 3 How Does Matter Change? 1 Copyright © Houghton Mifflin Harcourt Publishing Company 1

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Unit 13 Lesson 3 How Does Matter Change? Classifying Change Matter has physical properties that can be observed without changing the type of matter. Physical changes are changes to matter that do not affect the type of matter. Slicing an apple pie is an example of a physical change. 3

Unit 13 Lesson 3 How Does Matter Change? Classifying Change Chemical changes result in a change in the identity of matter. A chemical reaction is the process in which new substances are formed during a chemical change. Baking a pie in an oven is an example of a chemical change. 4

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Classifying Change Physical Smoke Chemical Ash Unit 13 Lesson 3 How Does Matter Change? Classifying Change Physical Smoke Chemical Ash 10

Tampering with Temperature Unit 13 Lesson 3 How Does Matter Change? Tampering with Temperature Physical changes to matter can happen faster or slower at different temperatures. How quickly a change occurs is called the rate of change. For example, water condenses more quickly on the outside of a very cold can than it does on a cool can. 11

Tampering with Temperature Unit 13 Lesson 3 How Does Matter Change? Tampering with Temperature 12

Tampering with Temperature Unit 13 Lesson 3 How Does Matter Change? Tampering with Temperature 13

Tampering with Temperature Unit 13 Lesson 3 How Does Matter Change? Tampering with Temperature 14

Unit 13 Lesson 3 How Does Matter Change? Faster or Slower? Increasing temperature can speed up the rate of a chemical change. Decreasing temperature usually slows down a chemical change. For example, the chemical changes that make food spoil are slowed down by keeping food in the refrigerator. 15

Unit 13 Lesson 3 How Does Matter Change? Faster or Slower? 16

Swelling and Shrinking Unit 13 Lesson 3 How Does Matter Change? Swelling and Shrinking Most matter expands when temperature goes up and contracts when temperature goes down. 17

Swelling and Shrinking Unit 13 Lesson 3 How Does Matter Change? Swelling and Shrinking 18

Swelling and Shrinking Unit 13 Lesson 3 How Does Matter Change? Swelling and Shrinking 19

Swelling and Shrinking Unit 13 Lesson 3 How Does Matter Change? Swelling and Shrinking Water expands when it freezes, making ice less dense than liquid water. 20

Swelling and Shrinking Unit 13 Lesson 3 How Does Matter Change? Swelling and Shrinking Some matter expands and contracts more than others. 21

Swelling and Shrinking Unit 13 Lesson 3 How Does Matter Change? Swelling and Shrinking 22

Unit 13 Lesson 3 How Does Matter Change? Adding It Up! During physical and chemical changes, matter may change its appearance or identity. Conservation of mass means the total mass of the matter before and after the physical or chemical change is the same. To conserve means “to save.” 23

Unit 13 Lesson 3 How Does Matter Change? Adding It Up! As water boils, for instance, it seems to disappear. However, the total mass of water vapor particles in the air equals the mass of water that boiled away. A chemical change turns one kind of matter into another. However, the mass of matter stays the same. Measuring conservation of mass can be hard, as you must collect and measure the mass of everything you begin with and end with. 24

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Unit 13 Lesson 3 How Does Matter Change? Adding It Up! 26

Unit 13 Lesson 3 How Does Matter Change? Fevers A fever is an increase in body temperature above the normal body temperature (about 37 °C). Low fevers, which are between 38 °C and 39 °C, help the body fight disease. High fevers, which are higher than 40 °C, can cause severe problems. 27

Unit 13 Lesson 3 How Does Matter Change? Fevers Temperature can increase for many reasons. For example, certain bacteria have materials the brain identifies as harmful. The brain sends out signals that cause an increase in chemical changes that produce energy. This raises your temperature to a level in which bacteria cannot survive. 28

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