Chapter 18 Introduction
The snow on the branch is changing from the solid to the liquid phase. Energy is involved in phase changes.
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CHAPTER 18
Observing Energy
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In this chapter, you will study
energy exchange in chemical reactions
heat, temperature, and thermal energy
the effect of heat on different substances
the energy associated with phase changes
All around you is evidence of energy exchanges. Any time matter moves or changes, energy is involved. Some expressions of energy are familiar, like the heat from a campfire or the radiant energy from the Sun. But energy can be a tricky concept to define. Chapter 18 of Unit 5: Fire introduces you to energy through observations of its effects on matter.