1. Matter and Change 11.1 Describing Chemical Reactions Chapter 11
11.2 Types of Chemical Reactions
11.3 Reactions in Aqueous Solution

2. Reaction(explosion of alkali metals)

3. 11.1 Chemical Reactions Examples of Chemical Reactions Rusting of iron
Burning (combustion) of wood
Cooking
Vinegar + Baking soda ->
Photosynthesis
6CO2 + 6H2O + Energy --> C6H12O6 + 6O2

4. Chemical reactions are like sentences.
Symbols  elements Formula  compound Equations  chemical reactions
Put letters together to make words. Put words together to make sentences.

5. Chemical reaction
a reaction that occurs when the atoms of one of more substances are rearranged to form different substances
a chemical change
Evidence of a chemical reaction
- Temperature change
- Color change
- Odor produced
- Formation of bubbles
- Appearance of a solid

6. Chemical Equations 2H2(g) + O2(g) 2H2O (l)
Reactants: elements or compounds to the left of the arrow that combine together in a chemical reaction
Products: elements or compounds to the right of the arrow that are produced in a chemical reaction
Coefficient: whole number before a chemical formula
Subscript: small lowered number after a chemical symbol
+ : represents “and”
: direction reaction progresses, yields or produces

7. C(s) O2(g) CO2 (g)
physical states of reactants and products are indicated by:
(s) = solid:    C(s)
(g) = gas:    CO2(g) 
(l) = liquid:    H2O(l)
(aq) = aqueous, dissolved in water,
NaCl(aq) is a salt water solution
(cr) = crystalline
= precipitate forms

8. Chemical Equations 2H2(g) + O2(g) 2H2O (l)
Identify the following and label
Reactants:
Products:
Coefficient:
Subscript:
+ define
define

9. Covalent Bonding GEN-U-INE
A molecule is a neutral group of atoms joined together by covalent bonds.
Diatomic molecules – molecules made up of the same element
Examples: O2 , H2 , N2, F2 , Cl2 , Br2 , I2
GEN-U-INE

10. Word and Formula Equations
Skeleton equation represents the reactants and products of a chemical reaction by their formulas.
Example: Na(s) + Cl2(g) NaCl(s)

11. Balancing Chemical Equations
balanced chemical equation – shows that each side of the equation has the same number of atoms of each element and mass is conserved
2 Na(s) Cl2(g) NaCl(s)
Law of conservation - in a chemical reaction matter is neither created nor destroyed
Chemical equations must be balanced using coefficients

12. Balancing Equations ____ K + ____ Cl2  ____ KCl
____ Ag + ____ O2  ____ Ag2O
____ H2 + ____ O2  ____ H2O
____ Na + ____ MgF2  ____ NaF + ____ Mg
____ N2 + ____ H2  ____ NH3

13. Balance the following equations
Mg + O2 ----> MgO KClO3 ----> KCl + O2 Na + MgCl2 ----> NaCl + Mg

14. Word and Formula Equations
A word equation is an equation represented by words.
Example: solid sodium plus chlorine gas reacts to produce sodium chloride

15. Steps for Balancing Equations
1) Write skeleton equation: assemble the correct formulas 2) Count the number of atoms of elements in reactants 3) Count the number of atoms of elements in products 4) Balance the elements one at a time by adding coefficients in front of a formula to make number of atoms equal on both sides of equation 5) Check to make sure equation is balanced and coefficients are in lowest possible ratio

16. Sample problems – Balancing Equations
Word Equation Hydrogen plus oxygen yields water Skeleton Equation Balanced Equation

17. Sample problems – Balancing Equations
Word Equation
Fluorine plus calcium bromide yields calcium fluoride and bromine
Skeleton Equation
Balanced Equation

18. Water and iron react to form iron III oxide and hydrogen
Propane (C3H8) burns in oxygen to form carbon dioxide and water

19. Do-Now
Identify and write the polyatomic ion using your ion chart. Include charge!
sulfate – hydroxide –
nitrate – phosphate –
Write the formulas for the following compounds. Must show charge and crisscross!
Potassium oxide 3. Iron (III) hydroxide
Calcium chloride 4. Barium sulfate

20. Chemical Reactions 11.3 Reactions in Aqueous Solution
Chapter 11
Chemical Reactions
11.1 Describing Chemical Reactions
11.2 Types of Chemical Reactions
11.3 Reactions in Aqueous Solution
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21. What happens to the wax when you burn a candle?
CHEMISTRY & YOU
What happens to the wax when you burn a candle?
When you burn a candle, a chemical reaction called combustion takes place.
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22. Classifying Reactions
What are the five general types of reactions?
Synthesis (or combination)
Decomposition
Singe-replacement
Double-replacement
Combustion
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23. 1. Synthesis Reactions (Combination)
Two (or more) reactants combine to form one product
general form: A B AB
specific types:
2 elements Fe S Fe+2S-2
2 compounds Ca+2O H2O Ca+2(OH)-12
1 element, 1 compound SO O SO3

24. 2. Decomposition Reactions
one reactant breaks down into two or more products
general form: AB A B
Examples: Na+1N Na N2
Ca+2(CO3) Ca+2O CO2
*decomposition reactions require energy
heat >
electricity --->
catalyst > 3

25. Classify each reaction as Synthesis or Decomposition
_________________ 2 Na + Cl2 ---> 2NaCl
_________________ CaCO > CaO + CO2
_________________ H2O > 2H2 + O2
_________________ CO O > 2CO2

26. 3. Single-Replacement
A single-replacement reaction is one in which one element replaces a second element in a compound
general form: Ao B+C Bo A+C-
Example: Zn + Cu+2(NO3) Cu + Zn+2(NO3)-1
general form: B+C Do B+D Co
Example: Na+Cl Br2 2 2
2Na+Br Cl2

27. 4. Double-Replacement general form: A+B- + C+D- ---> A+D- + C+B-2 3
general form: A+B C+D > A+D C+B-
Ex.: Na+(CO )-2 + Ba+2Cl > 2Na+Cl-1 + Ba+2(CO )-2
Specific type: Neutralization
Ca(OH) HCl ---> CaCl H2O
base acid yields salt water 2 3 2 3

28. Classify each reaction as Single Replacement or Double Replacement
__________ Mg Ag2SO4 ---> MgSO Ag
__________ 2NaF + CaCO > Na2CO CaF2
__________ SrBr KOH > Ca(OH) KBr
__________ 2LiCl Br > Cl LiBr

29. Combustion Rxns Ex: CH4 + 2 O2 CO2 + 2 H2O
-a reactant (hydrocarbon) and oxygen, O react and release energy, heat, and/or light, and products formed are CO2 and H2O
Ex: CH O CO H2O

30. Endothermic and Exothermic Reactions
We can indicate if energy was present in the reaction
Reactions that have energy as a reactant are called endothermic
- They require energy for the reaction to occur
- Also sometimes represented as → or →
Reactions that have energy as a product are called exothermic
- Energy happens as a result of the reaction
heat

31. Do Now Quiz on Balancing and Word Equations
Practice problems
1. Aluminum bromide + chlorine yield aluminum chloride and bromine
Zinc nitrate + lead yield lead (II) nitrate + zinc
Potassium chlorate when heated yields potassium chloride + oxygen gas