1. 2.4 Chemical Reactions Sponge: Set up Cornell Notes on pg. 13 2.4 Chemical Reactions Essential Question: Hydrogen peroxide (H 2 O 2 ) breaks down into water (H 2 O) and oxygen (O 2 ). Explain why this is a chemical reaction. What are the reactants and products? 2.4 Chemical Reactions Hydrogen peroxide (H 2 O 2 ) breaks down into water (H 2 O) and oxygen (O 2 ). Explain why this is a chemical reaction. What are the reactants and products? Key Concept: Life depends on chemical reactions Ch. 2 Quiz on Monday 9/8 Notebook Check on Wed 9/10

2. 2.4 Chemical Reactions On the top of pg. 13 When you hear the term chemical reaction, what comes to mind? Can you give examples of some chemical reactions?

3. 2.4 Chemical Reactions ANSWER Maybe you think of liquids bubbling in beakers. You probably do not think of the air in your breath, but most of the carbon dioxide and water vapor that you breathe out are made by chemical reactions in your cells

4. 2.4 Chemical Reactions

5. KEY CONCEPT Life depends on chemical reactions.

6. 2.4 Chemical Reactions Bonds break and form during chemical reactions. Chemical reactions change substances into different ones by breaking and forming chemical bonds Ex: iron + oxygen= rust

7. 2.4 Chemical Reactions Bill Nye- Chemical Reactions- 3 mins

8. 2.4 Chemical Reactions –Reactants are the substances changed during a chemical reaction. Reactants and Products –Products are the substances made by a chemical reaction. Ex: Cellular Respiration Oxygen and Glucose Carbon Dioxide and Water and Energy

9. 2.4 Chemical Reactions Cellular Respiration 6O 2 + C 6 H 12 O 6 --------  6CO 2 + 6H 2 O Reactants Products

10. 2.4 Chemical Reactions Pennies Experiment Please write a hypothesis for each of the following: Hypothesis –Pennies in Salt: –Pennies in Water: –Pennies in Vinegar: –Pennies in Vinegar and Salt: –Pennies in Water and Salt:

11. 2.4 Chemical Reactions Was your hypothesis correct? –Pennies in Salt: Nothing –Pennies in Water: Nothing –Pennies in Vinegar: Nothing –Pennies in Vinegar and Salt: Pennies get cleaned!!!! –Pennies in Water and Salt: Nothing Reactants: copper, vinegar, and salt Product: Hydrochloric Acid

12. 2.4 Chemical Reactions Mentos and Diet Coke Reactants: Products: Sodium and Water Reactants: Products: Reactants vs. Products: Pg. 12- Divide into 4 sections Elephant’s Toothpaste Reactants: Products: Gummi Bear Reactants: Products: Sodium and Chlorine Reactants: Products:

13. 2.4 Chemical Reactions Name the reactants (2) and products (3) in the Gummi Bear chemical reaction. Reactants: Sucrose- Gummi Bear Molten Potassium Chlorate Products: Carbon Dioxide Water Potassium Chloride On pg. 12:

14. 2.4 Chemical Reactions Name the reactants and products in the “Elephant’s Toothpaste” Video Reactants Hydrogen Peroxide Liquid Soap Potassium Iodide Products O 2 (oxidized) Foam Heat

15. 2.4 Chemical Reactions Name the reactants and products in the “Sodium and Water” and “Sodium and Chlorine” Reactants Sodium (toxic) Chlorine (toxic) Products Sodium Chloride(Safe!!!!) aka Table Salt Reactants Sodium (toxic) Water Products Hydrogen gas and Heat!!!!

16. 2.4 Chemical Reactions Name the reactants and products in the “Mentos and Diet Coke” Video Reactants Mentos Diet Coke Products CO2 Bubbles

17. 2.4 Chemical Reactions On the very bottom of pg. 12 : What is the difference between reactants and products (in your own words)? Give an example of each.

18. 2.4 Chemical Reactions Answer –Reactants are the substances we start with, it is what will be changed during a chemical reaction –Products are the substances or new things made by a chemical reaction. Ex: H2O2 + liquid soap + sodium iodide Ex: Oxidized Soap Foam + heat

19. 2.4 Chemical Reactions Sponge: Set up Cornell Notes on pg. 15 2.4 Chemical Reactions Essential Question: Describe how bonds break and form during chemical reactions 2.4 Chemical Reactions Describe how bonds break and form during chemical reactions Ch. 2 Quiz on Monday 9/8 Notebook Check on Wed 9/10

20. 2.4 Chemical Reactions Bond energy is the amount of energy that breaks a bond between two atoms –Energy is added to break bonds. –Energy is released when bonds form. Ex: Forming H 2 O molecules Ex: Breaking up H 2 O molecules using electricity

21. 2.4 Chemical Reactions Chemical equilibrium A reaction is at equilibrium when reactants and products form at the same rate. CO 2 + H 2 O H 2 CO 3 Carbon dioxide + Water--------------Carbonic acid When the CO 2 level is high in the blood, carbonic acid is formed When the CO 2 level is low in the lungs, carbonic acid is broken down

22. 2.4 Chemical Reactions All chemical reactions involve changes in energy Energy is both absorbed and released during chemical reactions –Energy is added to reactants to break bonds –When new bonds form in the products, energy is released

23. 2.4 Chemical Reactions Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction. * Like the energy you would need to push a rock up a hill Draw this mini picture

24. 2.4 Chemical Reactions Exothermic reactions release more energy than they absorb –Releases energy into its surroundings often as heat, light, or electricity –Products have lower bond energy than the reactants. Reactants-------  products + energy

25. 2.4 Chemical Reactions Endothermic reactions absorb more energy than they release –Absorbs energy from its surroundings in the form of heat –Lowers surrounding temperature –Products have a higher bond energy than the reactants

26. 2.4 Chemical Reactions Endothermic and Exothermic: Phase Change 4 min

27. 2.4 Chemical Reactions Pg. 14 On the top 1/3 of pg. 14: Please make a double-bubble map comparing and contrasting exothermic reactions with endothermic reactions. Exothermic Reactions Endothermic Reactions Video Notes Research (10 of each)

28. 2.4 Chemical Reactions Endothermic and Exothermic Reactions Clip 1min Exothermic and Endothermic Examples (4mins)

29. 2.4 Chemical Reactions Exothermic or Endothermic? Exo=Energy out (often as heat/light) Endo= absorbs energy

30. 2.4 Chemical Reactions With your group: Please use the internet/book to look up two-three of each Exothermic reactions –Reactants and products? Endothermic reactions –Reactants and products?

31. 2.4 Chemical Reactions Endothermic reactions Exothermic reactions Involve chemical reactions Absorb more energy than is released Releases more energy than is absorbed Products have more bond energy than the reactants Products have lower bond energy than the reactants Excess energy released as heat or light Involve changes in energy Energy is absorbed and released