1. The main tasks of Chap 8
Sect 1 - Writing reactions from word problems – challenging Sect 2 - Balance Equations—easiest Sect 3 - Classify Equations, Complete Equations—challenging Sect 4 – Write Net Ionic equations

2. Classifying Reactions
You will learn to recognize the different types of reactions AND
How to complete products (predict).

3. Combustion Reactions “Burning”
Oxygen is a reactant.
Energy is produced
Combustion of carbon compounds yield carbon dioxide(CO2) and water (H2O ).
Mg + O2  MgO
CH4 + O2  CO2 + H2O

4. Synthesis Reactions
Two or more elements or compounds combine to form ONE PRODUCT.
Mg + O2  MgO
H O2  H2O

5. Decomposition Reactions
ONE REACTANT (compound) breaks into elements or smaller compounds.
H2O  H O2
MgO  Mg + O2

6. Displacement Reactions
Also called Replacement reactions
Single Displacement/Replacement
Use the Activity series
Double Displacement/Replacement
Precipitation Reactions
Use the Solubility Rules
Acid Base Reactions

7. Single Displacement
Part of an ionic compound is removed and replaced by a new element.
ELEMENT + COMPOUND  COMPOUND + ELEMENT
There are 2 subtypes of single replacement reactions.
Cationic replacement
Anionic replacement

8. Single Displacement subtype CATIONIC REPLACEMENT:
If the Element is a Metal, it replaces the metal in the compound.
Cu AgNO3  Cu(NO3)2 + Ag

9. Single Displacement subtype: ANIONIC REPLACEMENT:
If the Element is a Non-metal, it replaces the non-metal in the compound.
Cl NaBr  NaCl Br2

10. Single Replacement Rxns
To determine if a Single Replacement Reaction really happens, use the ACTIVITY SERIES reference sheet.
If an element is higher on the chart, it will become a compound.
If the higher element is already in a compound, then NO reaction occurs

11. Double Replacement Rxns
Two Ionic Compounds that exchange partners.
XY AB  AY XB
Only Positive with Negative
Positive Ion listed first

12. Double Replacement Rxns
To determine if the reaction occurs, use the SOLUBILITY RULES.
A reaction occurs if a solid or water forms when two aqueous solutions of ionic compounds are mixed.
If the products are both aqueous ionic compounds, then no reaction occurs.

13. Solubility Rules info. Soluble = dissolves in water = (aq) = clear
Insoluble= doesn’t dissolve in water = SOLID = (s) = cloudy = precipitate = ppt

14. Section 4: Net Ionic Equations
Three ways to write the same equation (usually with double replacement rxns):
1. Complete Molecular Equation
2. Complete Ionic Equation
3. Net Ionic Equation

15. Dissolving (aq) separates the ions
NaCl (s) in water NaCl (aq)
NaCl (aq) means Na+(aq) + Cl- (aq)
The Ions move separately in solution.
In some equations we separate the ions and write the charges.

16. Complete Molecular Eqn
This is what we have been doing. Write the compounds with the ions together.
Example: NaCl (aq) + AgNO3 (aq)
AgCl (s) + NaNO3(aq)

17. Complete Ionic Eqns
Write the aqueous compounds as separate ions. Be sure to put the CHARGES ON THE IONS!
Keep the solid(insoluble) or water molecules together.
Example:
Na+ (aq) + Cl- (aq) + Ag+(aq) + NO3- (aq)
 AgCl (s) + Na+(aq)+ NO3-(aq)

18. Net Ionic Equations
Take the Complete ionic equation and remove any ion that is aqueous on both sides.
These ions are called Spectator Ions. OR
Find the Solid product or water, keep that part AND keep the reactant ions that made the solid or water.
Ex: Ag+ (aq) + Cl- (aq)  AgCl(s)

19. Net Ionic Eqns with Acids and Bases( H+ and OH-)
When acids (HA) and Bases (ZOH) mix, the H+ and OH- combine to become H2O(l). This is called a neutralization reaction. The water H2O(l) stays together like insoluble solids. So you keep it in the Net Ionic equation. Ex. H+ + OH-  H2O

20. Example: Complete and Net Ionic Equations page 1
Cu(NO3 )2 (aq) + NaOH(aq)  ????
1) Write Complete Molecular Equation:
Cu(NO3 )2 (aq) + NaOH(aq)  Cu(OH)2 (s) + NaNO3 (aq)
2) Write Complete Ionic Equation: [separate all (aq), put charges on ions; keep solids together.]
Cu+2(aq) +2NO3 -1(aq) + 2Na+1 (aq) + OH-1 (aq)
 Cu(OH)2 (s) + 2Na+1 (aq) + 2NO3 -1 (aq)
And then…

21. Example: Complete and Net Ionic Equations page 2
3) Write Net Ionic Equation: [eliminate spectator ions, keep ions that make solid, keep solids.] Cu+2(aq) + OH-1 (aq)  Cu(OH)2 (s)