1. Chemical Reactions

2. Chemical Reactions
When 2 or more elements chemically combine to form a “new” substance

3. Symbols: + used to separate 2 reactants or 2 products
 yields; used to separate reactant & product
(s) solid
(l) liquid
(g) gas
(aq) aqueous; dissolved in water
 catalyst= substance that speeds up a reaction but is NOT used up in the reaction

4. Chemical Equation Is a representation of a chemical reaction Two Parts
Reactants
Products

5. The arrow () divides an equation in half
Reactants vs Products
C + O2  CO2
The arrow () divides an equation in half
Reactants
The substance(s) that undergo the change
All things on the left side of the “”
Ex: C & O2
Products
The new substance(s) that form
All things on the right side of the “”
Ex: CO2

6. Id the Reactants and Products
2Cu + O2  2CuO
2KClO3  2KCl + 3O2
HCl + NaOH  NaCl + H2O
N2H4 + O2  N2 + 2H2O

7. Endothermic vs Exothermic
Reaction absorbs energy from its surrounding
Surrounding becomes colder
Exothermic
Reaction releases energy to the surrounding
Surrounding becomes warmer

8. Signs of a Reaction Production of a GAS Formation of a Precipitate
Fizzing, bubbling
Formation of a Precipitate
Insoluble solid
Energy is released
Light, heat
Color Change

9. Counting Atoms Number in front is called a coefficient
Coefficients are multiplied to all elements behind it
Subscripts go to what they just follow

10. Counting Atoms Practice
Mg(OH)2
3Ca(NO3)2
NH4OH

11. How Do I Balance an Equation?
Id the elements present
Count the amount of atoms on both sides of the “” for each element
Place coefficients in front of compounds and multiply to any subscript
Recount the atoms to see if they are equal

12. ____Cu + ____O2  ____CuO
Balancing Practice #1
____Cu + ____O2  ____CuO

13. ____N2H4 + ____O2  ____N2 + ____H2O
Balancing Practice #2
____N2H4 + ____O2  ____N2 + ____H2O

14. ____KClO3  ____KCl + ____O2
Balancing Practice #3
____KClO3  ____KCl + ____O2

15. Types of Reactions 4 Main Types 2 Special Types Synthesis
Decomposition
Single Replacement
Double Replacement
2 Special Types
Combustion Reaction
Neutralization Reaction

16. Synthesis Reaction A + B  AB
When 2 or more substances react to form a single substance
21
Dating: Becoming a Couple

17. Decomposition Reaction AB  A + B
When a compound breaks down into two or more substances
12
Dating: Breaking Up

18. Single Replacement Reaction A + BC  B + AC
A reaction in which one element trades places with another element in a compound
Element and Compound 
Dating: CHEATING

19. Double Replacement Reaction AB + CD  AD + BD
Where two different compounds exchange positive ions (cations) to form two new compounds
All compounds
(4 of them)
Dating: Swingers

20. Type Of Reaction Practice
Na3PO4 + 3KOH  3NaOH + K3PO4
P4 + 3O2  2P2O3
Pb + FeSO4  PbSO4 + Fe
CaCO3  CaO + CO2

21. Special Reaction: Combustion Reaction
When an element or compound reacts with oxygen producing energy in the form of heat and/or light
Reactants are always hydrocarbon & O2
Products are always CO2 & H2O
Ex:
CH4 + 2O2  CO2 + H2O

22. Reactions in Aqueous Solutions
Aqueous= dissolved in water
Over 70% of Earth’s surface is covered in water
About 66% of the human body is water
It is not surprising that many important chemical reactions take place in water.

23. Reactions in Aqueous Solutions continue…
Complete ionic equation = shows dissolved ionic compounds as dissociated free ions.
Spector ions = appears on both sides of an equation and is not directly involved in the reaction
Net ionic equation = shows only the particles that are directly involved in the chemical change