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Chapter 8.1: Describing Chemical reactions What I know about chemical reactions and conservation of matter?

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Presentation on theme: "Chapter 8.1: Describing Chemical reactions What I know about chemical reactions and conservation of matter?"— Presentation transcript:

1 Chapter 8.1: Describing Chemical reactions What I know about chemical reactions and conservation of matter?

2 Water How many different ways can you alter the water physically and still end up with water? List the ways you could alter the water chemically to create a new substance that is no longer the same as the original substance?

3 Sec 8-1: Chemical reaction evidence energy forms Heat Light Sound Electrical temperature change Gas Precipitate Color Odor

4 Also there are Physical change Melting points Density Condensation Evaporation Freezing

5 Example: determine whether each of the following is a chemical or physical change. 1. bending a toothpick 2.burning a match 3.burning sugar 4.making a cake from scratch 5.smashing a can 6.melting ice to water

6 How to represent Ch. R. Describe Word equation Formula equation Symbols (C, Na, and Fe) elements Formulas (NaOH) compounds Equations chemical reactions hydrogen (a gas) + sulfur yields hydrogen sulfide

7 Equation Reactants (on the left) Products (on the right) separated by arrow included physical states Examples: Iron + Oxygen Iron (III) oxide Methane + oxygen Carbon dioxide + water

8 Practice Problem When solid aluminum oxide and hydrogen gas are heated, molten aluminum and water vapor form. a. Write a word equation for the above reaction. Aluminum oxide + hydrogen aluminum + water b. Write an unbalanced formula equation using all appropriate symbols.

9 To write an unbalanced equation You must 1. Write the correct formulas of the reactants and the products. 2. Indicate physical state by putting a symbol after each formula. 3. Indicate catalyst by writing its formula above arrow. 4. Indicate heat and any change above arrow. Practice Problem: Write an unbalanced equation below word equation. Methane + oxygen Carbon dioxide + water


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