1. Science Module
8th Grade

2. HOT STUFF

3. TAKS Objective 3 – The student will demonstrate an understanding of the structures and properties of matter.
Complex interactions occur between matter and energy.

4. TEKS 8.10 (C)
The student knows that complex interactions occur between matter and energy. The student is expected to:
identify and demonstrate that loss or gain of heat energy occurs during exothermic and endothermic chemical reactions.

5. Learning Objectives
identify endothermic and exothermic reactions associated with chemical changes
Explain the loss or gain of heat during chemical reactions
Identify chemical and physical changes associated with endothermic and exothermic reactions

6. Heat- transfer of energy
Background
Heat- transfer of energy

7. Exothermic- heat energy EXITS the system
- ex. Combustion, evaporation of water
- surroundings usually feel warmer

8. 2Na(s) + Cl2(g)  2NaCl(s) + energy
Salt
An example of an exothermic reaction is the mixture of sodium metal and chlorine gas which yields table salt.
2Na(s) + Cl2(g)  2NaCl(s) + energy

9. Endothermic- heat energy ENTERS the system
- ex. Cold packs, melting ice
- surroundings usually feel cooler

10. How do cold packs work?
The outer pouch contains water. The inner pouch contains ammonium-nitrate.
When you “pop” the inner pouch, the chemical reaction absorbs heat energy from the surroundings. This is an endothermic reaction.
The temperature of the solution falls to about 35 F for 10 to 15 minutes.

11. sunlight + 6CO2(g) + 6H2O(l)  C6H12O6(aq) + 6O2(g)
Photosynthesis
During photosynthesis, plants absorb the energy from the sun to convert carbon dioxide and water into glucose and oxygen.
sunlight + 6CO2(g) + 6H2O(l)  C6H12O6(aq) + 6O2(g)

12. Physical change- change in size, shape or state of matter

13. Chemical Reaction - process in which one or more substances are changed into others. Chemical reactions are accompanied by a loss or gain of energy.

14. Chemical reactions always produce heat
True or False
Chemical reactions always produce heat

15. Chemical reactions can release or absorb heat, but can also create
light, sound or electricity!

16. Heat can be lost, destroyed
True or False
Heat can be lost, destroyed
or just disappear

17. Law of Conservation of Energy
Heat energy is transferred from one object to another, or is transferred to another form of energy, but never disappears.
Law of Conservation of Energy

18. Color change is always a physical property
True or False
Color change is always a physical property

19. Color is a physical property. Color change can be the result
of a chemical change.

20. ENGAGE
Cold Packs
Rubber Bands
Glo-sticks

21. EXPLORE
Hot or Not
students explore endothermic and exothermic chemical reactions using baking soda and calcium chloride

22. EXPLAIN List 3 physical properties of matter.
List 3 physical properties for:
Calcium chloride
Baking soda
Phenol red solution

23. Describe what happens with baking soda and calcium chloride are mixed.
Describe what happens with baking soda, calcium chloride and phenol red are mixed.
What are evidences of chemical change?

24. Is this an endothermic or exothermic reaction? How do you know?
Give three examples of exothermic reactions in everyday life.

25. ELABORATE Ice Ice Baby Baking soda and vinegar
Is this endothermic or exothermic? How do you know?
Give 3 examples of everyday endothermic reactions.

26. Ice Cream Are the changes physical or chemical?
Is the ice cream endothermic or exothermic? How do you know?
Is the ice/salt mix endothermic or exothermic? How do you know?

27. EVALUATION Complete Type of Change? Endo/Exo chart
Complete graph analysis questions