1. Ch 21 Chemical Changes Bellwork:
In your Science Notebook, define the following terms:
Chemical reaction
Reactant
Product
Chemical equation
Coefficient
Balanced Chemical Equations

2. Ch 21 Chemical Changes
CLE Investigate chemical and physical changes.
CLE Apply the Laws of Conservation of Mass/Energy to balance chemical equations.

3. What are we going to learn today?
I CAN: Identify reactants and products of a chemical reaction.
I CAN: Determine how a chemical reaction satisfies the law of conservation of mass.
I CAN: Determine how chemists express chemical changes using equations.

4. What do we already know? List three examples of chemical reactions:
One unique observation per pair.
(How do chemical changes differ from physical changes?)
Definition of equation:
A statement of the equality or equivalence of mathematical or logical quantities
Law of Conservation of Mass…in a chemical reaction, matter is neither created nor destroyed.

5. Describing Chemical Reactions
a change in which one or more substances are converted into new substances
Reactant:
the substances that react
Products:
the new substances produced

6. Writing Equations Reactants --------Yield-------------- Products - +
(aq)
Heat, light, electricity

7. Antoine Lavoisier Father of Modern Chemistry Chemistry textbook
Chemical nomenclature
IUPAC
Conservation of Mass
Pg 632 Mass of candles and oxygen before burning is exactly equal to mass of remaining candle and gaseous products

8. Basketball Team Equations
15 Index cards - 5 Guards, 5 Forwards, 5 Centers
Write the chemical equation for a team.
Write the chemical formula for a team.
How is this equation like a chemical equation?
What happens to the cards left over? How does this activity demonstrate the law of conservation of mass?

9. Exit ticket
When making soap, if 890 g of a specific fat react completely with 120 g of sodium hydroxide, the products formed are soap and 92 g glycerin. Calculate the mass of soap formed to satisfy the law of conservation of mass. Show your work and write a formula.

10. In your Science Notebook:
Ch 21 Chemical Changes
Bellwork:
In your Science Notebook:
1 Write a short definition/description of each vocabulary word in your own words.
2. Draw an illustration for each work to demonstration your understanding.

11. Exit ticket
When making soap, if 890 g of a specific fat react completely with 120 g of sodium hydroxide, the products formed are soap and 92 g glycerin. Calculate the mass of soap formed to satisfy the law of conservation of mass. Fat + sodium hydroxode - soap + glycerin 890 g g - X g + 92 g glycerin 890 g g = 1010 g – 92 g = 918 g soap

12. Ch 21 Chemical Changes
CLE Investigate chemical and physical changes.
CLE Apply the Laws of Conservation of Mass/Energy to balance chemical equations.

13. What are we going to learn today?
I CAN: Identify reactants and products of a chemical reaction.
I CAN: Determine how a chemical reaction satisfies the law of conservation of mass.
I CAN: Determine how chemists express chemical changes using equations.

14. Exit Ticket
1. What coefficient is assumed if no coefficient is written before a formula in a chemical equation?
2. Explain why the sum of the coefficients on the reactant side of a balanced equation does not have to equal the sum of the coefficients on the product side of the equation.

15. Bellwork: Vocabulary Quiz Today – Study!
Ch 21 Chemical Changes
Bellwork: Vocabulary Quiz Today – Study!

16. What are we going to learn today?
Identify what is meant by a balanced chemical equation.
Determine how to write balanced chemical equations.

17. Balancing Chemical Equations
1. Write a chemical equation for the reaction using formulas and symbols.
Li(s) + H2O  LiOH(aq) + H2 (g)

18. Balancing Chemical Equations
2. Count the atoms in reactants and products.
Li(s) + H2O  LiOH(aq) + H2 (g)
Li = 1 Li = 1
H = 2 H = 3
O = 1 O = 1

19. Balancing Chemical Equations
3. Choose coefficients that balance the equation. (Subscripts cannot be changed.)
Li(s) + H2O  LiOH(aq) + H2 (g)

20. Balancing Chemical Equations
3. Choose coefficients that balance the equation. (Subscripts cannot be changed.)
Li(s) H2O  LiOH(aq) + H2 (g)

21. Balancing Chemical Equations
3. Choose coefficients that balance the equation. (Subscripts cannot be changed.)
Li(s) + 2 H2O  2 LiOH(aq) + H2 (g)

22. Balancing Chemical Equations
3. Choose coefficients that balance the equation. (Subscripts cannot be changed.)
2 Li(s) H2O  2 LiOH(aq) + H2 (g)

23. Balancing Chemical Equations
4. Recheck numbers of each atom on each side of the equation .
2 Li(s) H2O  2 LiOH(aq) + H2 (g)
Li = 2 Li = 2
H = 4 H = 4
O = 2 O = 2

24. Exit Ticket
1. What coefficient is assumed if no coefficient is written before a formula in a chemical equation?
2. Explain why the sum of the coefficients on the reactant side of a balanced equation does not have to equal the sum of the coefficients on the product side of the equation.

25. Exit Ticket K + AlCl3  KCl + Al Balance the following equation:
Which of the 5 types of chemical reactions does this represent? (Combustion, synthesis, decomposition, single displacement, double displacement)

26. Section 3 Classifying Chemical Reactions
Bellwork: Language of Science
In your Science Notebook, define the following terms:
Precipitate
Oxidation
Reduction
Catalyst
Inhibitor

27. Ch 21 Chemical Changes
CLE Investigate chemical and physical changes.
CLE Apply the Laws of Conservation of Mass/Energy to balance chemical equations.

28. What are we going to learn today?
I CAN: Identify what is meant by a balanced chemical equation. I CAN: Determine how to write balanced chemical equations. I CAN: Identify five types of chemical reactions.

29. Types of Chemical Reactions
Combustion Reaction:
Substance reacts with oxygen to produce energy in the form of heat and light
2 Mg O2  2 MgO light
C3H O2  4 H2O CO energy
Many combustion reactions fit into other categories.
(carbon+oxygencarbon dioxide is synthesis)

30. Types of Chemical Reactions
Synthesis Reaction:
Two or more substances combine to form another substance
A + B  AB
2 H2 + O2  2 H2O
(powers some rockets)
Oxygen+Iron+Water  hydrated Iron (II) oxide (Rust)

31. Types of Chemical Reactions
Decomposition Reaction: reverse of synthesis
One substance breaks down (decomposes) into two or more substances.
AB  A + B
Most require heat, light or electricity.
2 H2O ---electricity---  2 H O2

32. Types of Chemical Reactions
Single Displacement Reaction:
One element replaces another element in a compound
A + BC  AC + B
Cu AgNO3  Cu(NO3) Ag
Copper wire in silver nitrate…Cu is more active than Ag , replaces silver, forms blue copper (II) nitrate
Don’t cook iron containing vegetables like spinach in aluminum pans – Al can displace Fe in food

33. Types of Chemical Reactions
Double Displacement Reaction:
The positive ion of one compound replaces the positive ion of the other to form two new compounds.
AB + CD  AD + BC
Two ionic compounds in solution combine…forms precipitate, water or gas
Precipitate – insoluble compound that comes out of solution

34. Types of Chemical Reactions
Double Displacement Reaction:
Ba(NO3) K2SO4  BaSO KNO3

35. Oxidation – Reduction Reactions
Redox Reactions – paired reactions Oxidation – loss of electrons – becomes more positive – “oxidized” Reduction – gain of electrons – becomes more negative – “reduced” Electrons pulled from one atom (oxidation) are gained by another atom (reduction) Often involve oxygen which is very reactive, pulling electrons from metallic elements - rust, corrosion

36. Section 4 Chemical Reactions and Energy
Bellwork:

37. Ch 21 Chemical Changes
CLE Investigate chemical and physical changes.
CLE Apply the Laws of Conservation of Mass/Energy to balance chemical equations.

38. What are we going to learn today?
I CAN: Identify the source of energy changes in chemical reactions. I CAN: Compare and contrast exergonic and endergonic reactions. I CAN: Examine the effects of catalysts and inhibitors on the speed of chemical reactions.

39. Identify the source of energy changes in chemical reactions.
All chemical reactions release or absorb energy as chemical bonds are broken and formed.
Thermal energy (heat), Light, Sound, Electricity
Chemical bonds are the source of this energy.
Bonds broken – requires energy
Bonds formed – energy released

40. Compare and contrast exergonic and endergonic reactions.
Exergonic – chemical reactions that release energy
Less energy is required to break original bonds than is released when new bonds form
Glow stick – visible light
Dynamite combustion – sound energy
Exothermic – thermal energy released
Provide most power used in homes and industry
Wood fire, heat packs, dynamite, burning fossil fuels
Coal/Petroleum/Natural gas + O2  CO2(g) + energy

41. Compare and contrast exergonic and endergonic reactions.
Endergonic – chemical reactions that absorb energy in the form of light, thermal energy, electricity
Requires more energy to break bonds than is released when new ones are formed
Endothermic – thermal energy absorbed
Epsom salt (physical change), cold pack
Barium hydroxide + ammonium hydroxide + energy… reaction absorbs so much energy that water freezes

42. Examine the effects of catalysts and inhibitors on the speed of chemical reactions
Catalyst – substance that speeds up a chemical reaction without being permanently changed itself
Catalyst can be recovered and reused
Some reactions proceed too slowly to be useful
Increase rate of chemical reactions
Inhibitor – used to slow down a chemical reaction
Food preservatives, BHT, BHA, prevent food spoilage
Decrease rate of chemical reactions
Do not change amount of product produced, only change rate of production

43. Study Guides Test (Th 1/12) – 100 pts
10 chemical equations to balance, ID type of reaction
Mult Choice/Matching on Types of Reactions
1st set Language of Science
Packet pages, notes, vocab
Similar, not same, examples
Quiz (Fri 1/13) – 15 pts
Mult Choice/Matching on 2nd set of Language of Science Vocab