Introduction

How can you identify that a chemical reaction has occurred?



B9.1 egg boiling in water
A pot of water boiling on the stove creates gas bubbles; however, this is a physical change, not a chemical reaction. When an egg is placed in the boiling water, the proteins in the egg will undergo a chemical reaction and change from a gel-like liquid into a firm solid.

In this lesson, you will learn how to identify a change as a chemical reaction, based on observations.

  Targets

By the end of this lesson, you will be able to

  • describe the evidence for chemical changes
  • differentiate between exothermic and endothermic reactions

  Watch This

Blue-Bottle Reaction @ Wikimedia https://adlc.wistia.com/medias/6lfuv7xqlc


Watch this video that will introduce you into the world of chemical changes. What evidence do you see that would indicate that this is a chemical change? Is there evidence that would indicate that this is not a chemical change? This will help get you in the right mindset for this lesson.

The colour change would indicate a chemical reaction has occurred. However, it appears to be easily reversed.