1. CHEMICAL REACTIONS Equations Types of Reactions Prediction of Products
Diatomic Molecules
Solubility Rules

2. Chemical Reactions
Substances undergo changes to produce new substances with different properties
Represented by chemical equations
Obey the law of conservation of mass
Can be endothermic or exothermic

3. Evidence of a Chemical Reaction
Change in temperature
Formation of a precipitate (insoluble compound)
Change in color
Smoke
Bubbles
Production of light

4. Chemical Equations
Use symbols and formulas to represent chemical reactions
Include state symbols:
(s) solids
(l) liquids
(g) gases
(aq) solid dissolved in water…see solubility chart

5. Special Elements Diatomic Molecules Others Hydrogen Nitrogen Oxygen
Fluorine
Chlorine
Bromine
Iodine
Others
Phosphorus (P4)
Sulfur (S8)

6. Parts of a Chemical Equation
Reactants
Substances that enter into a reaction
Products
Substances that are produced by a reaction
State symbols
Indicate the state of matter for each substance in the reaction
Coefficients
Indicate the number of molecules or atoms of each substance in a reaction

7. Chemical Equation PRODUCTS REACTANTS State symbols Coefficients
Yields/Produces
PRODUCTS
REACTANTS
2H2 (g) O2 (g)  H2O (l)
State symbols
Coefficients

8. Why Balance?
Equations must be balanced in order to satisfy the law of conservation of mass
According to “the law” the mass of the reactants must be equal to the mass of the products

9. Find Masses
2H2 (g) O2 (g)  H2O (l)

10. How to Balance an Equation
Write the correct formulas/symbols for the reactant and the products (check for diatomic molecules)
Determine the number of atoms/ions of each element in the reactants and the products
Add/change coefficients to make the numbers of atoms/ions equal for reactants and products. NEVER change subscripts!!!

11. Helpful Hints Balance oxygen last and hydrogen next to last
Keep polyatomic ions “together” as long as they are together in the reactants and in the products

12. Balancing Equations Examples
MgCl2 + K  KCl + Mg
Pb(SO4)2 + KCl  PbCl4 + K2SO4

13. Balancing Equations Practice
H2O2  H2O + O2
Na2CO3 + HCl  NaCl + H2O + CO2
FeCl3 + NH4OH  Fe(OH)3 + NH4Cl
S8 + O2  SO3

14. Word Equations
Expresses a chemical reaction in words rather than using formulas and symbols
You will need to be able to convert from word equations to chemical equations and vice versa

15. Write word equations for:
H2O2  H2O + O2
Na2CO3 + HCl  NaCl + H2O + CO2
FeCl3 + NH4OH  Fe(OH)3 + NH4Cl
S8 + O2  SO3

16. Types of Reactions Synthesis Decomposition Single-Replacement
Double-Replacement
Combustion

17. Synthesis + Two or more substances react to form one substance
General equation: A + X  AX Mg O +

18. Decomposition
One substance breaks down (decomposes) to form more than one substance
General Equation: AX  A + X K Cl +

19. Single Replacement
A single element takes the place of another element in a compound.
Can be a cation replacing another cation or an anion replacing another anion
The “replacer” must be more reactive than the “replacee”
See the Activity Series of Metals
General Equation: AX + B  BX + A
AX + Y  AY + X

20. Activity Series of MetalsK Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au
Decreasing Reactivity
Will replace H+
from acids and water
Will replace H+
from acids ONLY
Activity Series of Metals

21. Single Replacement Li K F +
No RXN Li Li + Br Br + F F

22. Will It React?
Virtual Lab

23. Double Replacement
The cations and anions in two compounds switch places
The cation of one compound combines with the anion of the other compound and vice versa
General Equation: AX + BY  AY + BX

24. Double Replacement K Br Na Cl +

25. Combustion A substance reacts with oxygen Combustion means “burn”
The complete combustion of a hydrocarbon produces carbon dioxide and water
Incomplete combustion can lead to the production of carbon monoxide

26. Identify the Type of Reaction
Sb + O2  Sb4O6
H3BO3  H4B6O11 + H2O
Al + FeO  Al2O3 + Fe
FeCl3 + NH4OH  Fe(OH)3 + NH4Cl
C7H16 + O2  CO2 + H2O