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Lesson 6
The Changes That Occur
Two substances are mixed in a beaker. How do you know that a chemical reaction has occurred?
The change in colour that occurs where the two liquids mix indicates that a reaction has
occurred. The changes that occur when you mix substances together tell you that a reaction has
occurred. In a chemical reaction, the substances you start with are not the same substances you
end up with.
Turn to page 28 of the textbook and read "The Changes That Occur."
4. The substances present before a reaction are called the ________________.
5. The substances present after a reaction are called the _________________.
6. List the three main indicators that a chemical reaction has occurred.
7. Are there any other indicators of a chemical reaction?
8. What evidence is there that a reaction has occurred in Figure 2.6?
Turn to page 29 of the textbook and read "Combustion and Neutralization."
9. A chemical reaction in which a fuel is burned in the presence of oxygen is called a
___________ reaction.
10. The products of burning a candle in the presence of oxygen are _____________ and
______________.
11. Chemical reactions involving an acid added to a base to produce a new compound and water
are called _____________ reactions.
12. What area of homemaking often involves acid-base reactions?
13. Taking an antacid is a common neutralization reaction. In this reaction you take a base to
neutralize the excess acid in your stomach.
a. What is the name of the base commonly found in antacid medication?
b. Write out the word equation for the neutralization of stomach acid with an antacid.
c. Which compounds are formed?
14. Toothpastes contain various ingredients to help clean your teeth. Read the information in
"Did You Know?" on page 29 of the textbook. List the ingredients in your toothpaste. How many
of the ingredients in your toothpaste match those given in the "Did You Know?" section?