1. Chemical Reactions

2. Which of the following are examples of chemical change?
Digestion
Melting an ice cube
Running a car
Decomposition
Dissolving sugar in water
Boiling water
Photosynthesis
Cellular Respiration
A nail rusting

3. Chemical Reaction (or Chemical Change)
The process by which the atoms of one or more substances are REARRANGED to form different substances

4. Evidence of a Chemical Reaction
Temperature change
Exothermic Reaction-heat is given off
Endothermic Reaction-heat is absorbed
Exothermic Reaction
Endothermic Reaction

5. Classify each of the following as endothermic or exothermic.
A log burning in the fireplace.
A chemical ice pack
Baking soda is added to vinegar causing the test tube to become cold to the touch.
A hand warmer
Drain cleaner is added to a clogged pipe causing the pipes to become warm.
Photosynthesis
Cellular respiration
Baking a cake

6. Evidence of a Chemical Reaction
Color Change

7. Evidence of a Chemical Reaction
Production of an Odor

8. Evidence of a Chemical Reaction
4. Production of a gas (bubbles)

9. Evidence of a Chemical Reaction
5. Formation of a solid called a precipitate

10. Evidence of a Chemical Reaction
6. Production of other forms of energy such as light.

11. Chemical equation +  (s) Solid state (l) Liquid state (g) (aq) ∆
Separates 2 or more reactants or products 
Separates reactants from products
(s)
Solid state
(l)
Liquid state
(g)
Gaseous State
(aq)
Dissolved in water ∆
Heat is added
A written expression of a chemical reaction
Reactant  Product
(Starting Substance) (New substance
that forms)
Symbols used in chemical equations

12. Chemical Equations
Reaction: Solid aluminum reacts with liquid bromine to produce solid aluminum bromide.
Word Equation-the description of a reaction is written according to the following format:
Reactant 1 + Reactant 2  Product 1
Aluminum (s) + Bromine (l)  Aluminum Bromide (s)

13. Chemical Equations Word Equation
Aluminum (s) + Bromine (l)  Aluminum Bromide (s)
Skeleton Equation-formulas/symbols are used to represent names of compounds and elements.
Al (s) Br2(l)  AlBr3 (s)

14. Practice writing word and skeleton equations:
Write the equation for the reaction observed in lab.
Write the equation for the endothermic reaction that was observed.

15. Chemical Equations
A complete chemical equation is a statement that uses chemical formulas, states of matter and coefficients to represent the substances involved and how much is needed to fully react.

16. Balancing Chemical Equations
A chemical equation is not complete until the atoms on the reactant side equal the atoms on the product side. COEFFICIENTS (NUMBERS IN FRONT OF THE FORMULA) are used to balance equations.
___Al (s) ___Br2(l)  ___AlBr3 (s)

17. Why must we balance equations?
Law of conservation of mass-during chemical equations, matter cannot be created or destroyed. Atoms are only rearranged.
Therefore, the number and kinds of atoms making up the reactants must be the same as those making up the products.
Mass of reactants = Mass of products

18. Types of Chemical Reactions
Synthesis Reactions-
Two or more substances combine to form a single product
General Form: A + B  AB
Example
N2 (g) + 3H2(g)  2NH3 (g)
Na2O + H2O  2NaOH

19. Types of Chemical Reactions
Decomposition Reactions-
A single reactant breaks down into two or more elements or new compounds
General Form: AB  A + B
Example:
NH4NO3 (s)  N2O (g) + 2H2O (g)
2HgO  2Hg + O2

20. Types of Chemical Reactions
Single Replacement reactions-
Atoms of one element replace atoms of another element in a compound
General Form: A + BC  B + AC
Metals replace metals and nonmetals replace nonmetals
Example:
Cu(s) + AgNO3(aq)  2Ag(s) + Cu(NO3)2(aq)
Cu (metal) replaces Ag (metal) in the compound because it is more reactive.
Cl2 + NaBr  Br2 + NaCl
Cl2 (nonmetal) replaces Br2 (nonmetal) because it is more reactive.

21. Types of Chemical Reactions
How do I know if an one atom can replace another?
There is a table of reactivity. It ranks metals from most reactive (at the top) to least reactive (at the bottom)

22. Reactivity Table Most Active Nonmetals F Cl Br I
Most Active Metals Li Rb K Ca Na Mg Al Mn Zn Fe Ni Sn Pb Cu Ag
Least Active Metals Pt Au
Most Active Nonmetals F Cl Br I
Least Active Nonmetals

23. Which of the following reactions can take place?
I2 + NaF  F2 + NaI
Mg + HCl  MgCl2 + H2
Cu + MgSO4  CuSO4 + Mg
K + NaOH  KOH + Na

24. Types of Chemical Reactions
Double Replacement Reactions-
Atoms in one compound replace atoms in another compound
General Form: AB + CD  AD + CB
NaOH (aq) + CuCl2(aq)  2NaCl(aq) + Cu(OH)2 (s)

25. Types of Chemical Reactions
Combustion Reaction-
Combustion reactions occur when oxygen combines with a substance and energy is released (exothermic)
General Form: CxHy + O2  CO2 + H2O
Examples:
C (s) + O2 (g)  CO2(g)
CH4 + O2  CO2 + H2O

26. For each of the following, identify the type of reaction
Fe + H2SO4  Fe2(SO4) H2
C2H O2  H2O CO2
Al O2  Al2O3
KClO3  KCl O2
KNO H2CO3  K2CO HNO3

27. Specific Rules for Reactions
Decomposition
Metallic Carbonates, when heated, breakdown to form metallic oxides and carbon dioxide
ZnCO3 (s)  ZnO (s) + CO2 (g)

28. Specific Rules for Reactions
Decomposition
Many Metallic Hydroxides when heated, decompose into metallic oxides and water
Mg(OH)2 (s)  MgO(s) + H2O (g)

29. Specific Rules for Reactions
Decomposition
Metallic chlorates, when heated, decompose into metallic chlorides and oxygen gas.
KClO3 (s)  KCl (s) + O2 (g)

30. Specific Rules for Reactions
Single Replacement Reaction
Replacement of hydrogen in acids by metals
2Al (s) + 6HCl (aq)  2AlCl3 (aq) + 3H2 (g)

31. Specific Rules for Reactions
Single Replacement
Replacement of hydrogen in water by metals
Fe (s) + 2H2O (l)  Fe(OH)2 (s) + H2 (g)

32. Specific Rules for Reactions
Double Replacement Reaction
Neutralization Reaction is a type of chemical reaction that occurs between an acid and base to produce a salt and water.
Ca(OH)2 (aq) + 2HCl (aq)  CaCl2(aq) + 2H2O (l)