PhysicalScienceSOLPS.5
I.  Characteristics of Chemical Reactions
A. Definition à old bonds are broken
and new bonds are formed making a
new substance
B. Chemical equation à uses chemical
formulas and symbols to describe a
chemical reaction
**Example
2H2 + O2 à 2H2O
C. Parts of an equation
1. Reactants à left side of equation
2. Products à right side of equation
3. Yield(à) – means produces
4. Plus sign (+)à means combines/and
5. Subscripts à the # of atoms
6. Coefficientsà the # of molecules
II. Balancing Chemical Equations
A. Purposeà to show the law of
conservation of matter
** Reactants = Products
B. Use coefficients to balance the
equation
C. Examples: What goes in the blank?
__2_KClO3 à __2__KCl + 302
4Al + 3O2 à __2_Al2O3
III. Types of Chemical Reactions
*2 General/Broad Types of reactions:
A. Endothermic Reaction
1. Definition– absorbs energy
2. 6CO2 + 6H20 + lightà C6H12O6 + 6O2
B. Exothermic Reaction
1. Definition – releases energy
2. 2Na + 2H2O à 2NaOH + H2 + heat
* 4 Specific Types of Reactions
C. Synthesis Reaction
1. Def. à 2 or more substances
combine to form a new substance
2. Format = A+B à AB
3. Ex. = 2Na + Cl2 à 2NaCl
2 Na + Cl2
→ 2 Na Cl
D. Decomposition Reaction
1. Def.- one substance breaks down
into 2 or more smaller substances
2. Format = AB à A + B
3. Ex. = 2NaCl à 2Na + Cl2
2 Na Cl
→ 2 Na + Cl2
E. Single Replacement Reaction
1. Def. – one element replaces another
one in a compound
2. Format = AB + C à CB + A
3. Ex. = CuCl2 + Zn à ZnCl2 + Cu
Cl
Cu
Cl + Zn →
Cl
Zn
+
Cu
Cl
F. Double Replacement Reaction
1. Def.- 2 molecules create 2 new
molecules
2. Format = AB + CD à AD + CB
3. Ex. = MgO + CaS à MgS + CaO
Mg
O
+
Ca
S
→
Mg
S
+
Ca
O