5.1 Notes
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Chemical reactions involve the rearrangement of atoms and the formation of new compounds with different physical properties than the original reactants. Signs that a chemical reaction has occurred include the formation of a gas, bubbles, an odor, smoke, a new solid, or a change in color. Chemical reactions also involve the absorption or release of energy. Exothermic reactions release energy overall as the products have less stored energy than the reactants. Endothermic reactions absorb energy overall as the products have more stored energy than the reactants.
5.1 Notes
- 1. 5.1 The nature of chemical reactions Pages 148 - 153
- 2. Goal 1 Understand what occurs during a chemical reaction and recognize the signs
- 3. Each compound or element Has its own physical properties Taste Melting temp Boiling temp Color
- 4. Chemical reactions rearrange atoms Reactants at start Compounds are changed Products at end New properties shown 2H 2 + O 2 2 H 2 O
- 5. Signs of chemical reaction Gas formed Bubbles Odor Smoke
- 6. Signs of chemical reaction New solid formed
- 7. Sodium sulfide + cadmium nitrate cadmium sulfide (clear liquid) (clear liquid) (yellow solid)
- 8. Signs of chemical reaction Color change
- 9. Signs of chemical reaction Heat / light energy release
- 10. Signs of chemical reaction Corrosion
- 11. Goal 2 Describe energy movement and the difference between exothermic and endothermic reactions
- 12. Break bonds Reactant break-up Energy added Heat, light, electricity, sound Form bonds Product formation Energy released 2H 2 + O 2 2 H 2 O
- 13. Energy is conserved in chemical reactions All accounted for (what goes in…) Absorbed Stored Released
- 14. Exothermic Overall reaction releases energy Reactants had more stored energy than products
- 15. Endothermic Overall reaction absorbs energy Reactants had less stored energy than products