Chemical Reactions
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Reaction Review
Writing and Balancing Chemical Equations
Types of Reactions
Predicting Products
Predicting States of Matter
Nature of Reactions
Content
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Reaction Review
Balancing Chemical Equations
Writing Chemical Equations
Types of Reactions
Predicting Products
Predicting States of Matter
Nature of Reactions
3 Types of Compounds
Ionic
Metal + Non-Metal
Cation (+) + Anion (-)
Covalent / Molecular
Non-Metal + Non-Metal
Prefixes
Acid
+
H + Anion
Chemical Reactions
have two parts….
Reactants
CH4
+
O2
Reactants
Products
CO2
+ H2O
Products
The order you
list the reactants
and products
never matters
Chemical: Involves a change in chemical
composition (atoms are rearranged).
Signs include:
•Heat, Light, Sound (energy released/absorbed)
•Formation of a new gas (bubbles, fizzes)
•Formation of a precipitate
Mass is neither lost nor gained
(Law of Conservation of Mass)
for both changes.
Chemical change
Physical changes
Content
• Reaction Review
• Writing and Balancing Chemical Equations
Chapter 8 pages 267 - 289
• Types of Reactions
• Predicting Products
• Predicting States of Matter
• Nature of Reactions
HONClBrIF
The Missing Link
HONClBrIF: All of these elements exist as
diatomic molecules (not single atoms) in nature:
H2 O2 N2 Cl2 Br2 I2
F2
A group of diatomic molecules
3 Requirements of a Chemical Equation
• The equation must represent all the facts
• All chemical formulas must be written
correctly
– Charges must add to zero
– Cation, followed by anion
– Diatomic elements written as diatomics
• The Law of Conservation of Matter applies
– Equation must balance
Tips to Balancing Equations
1. Write correct skeletal equation
2. Balance the equation so each side has
the same number of atoms of each
element
3. Balance using coefficients, never
change subscripts
ex: __Fe + __O2  __Fe2O3
Tips to Balancing Equations
4. Coefficients apply to all the elements
in a compound
ex. 3C4H10
CH4 + 2O2
CO2 + 2H2O
Coefficients indicate the number of each substance.
To find the # of atoms, multiply the coefficient by subscripts.
3C4H10
12 C
CH4 + 2O2
CO2 + 2H2O
Coefficients indicate the number of each substance.
To find the # of atoms, multiply the coefficient by subscripts.
3C4H10
30 H
12 C
CH4 + 2O2
CO2 + 2H2O
Coefficients indicate the number of each substance.
To find the # of atoms, multiply the coefficient by subscripts.
3C4H10
2Ca(NO3)2
30 H
12 C
CH4 + 2O2
CO2 + 2H2O
Coefficients indicate the number of each substance.
To find the # of atoms, multiply the coefficient by subscripts.
3C4H10
12 C
30 H
2Ca(NO3)2
2 Ca
CH4 + 2O2
CO2 + 2H2O
Coefficients indicate the number of each substance.
To find the # of atoms, multiply the coefficient by subscripts.
3C4H10
12 C
30 H
2Ca(NO3)2
2 Ca
4N
CH4 + 2O2
CO2 + 2H2O
Coefficients indicate the number of each substance.
To find the # of atoms, multiply the coefficient by subscripts.
3C4H10
12 C
30 H
2Ca(NO3)2
12 O
(2x3x2)
2 Ca
4N
Tips to Balancing Equations
5. O’s and H’s should be balanced last
6. Balance polyatomic ions as units
(don’t count the atoms inside).
7. When you’re having trouble, put a 2
as the first coefficient and try again
(then 3, then 4, …)
Example:
__Al
+ __I
2
3 2
2
__AlI
3
Examples:
6 2
__P4 + __Cl
2
__ CaCl2 + __NaNO
3
4
__PCl
3
2
__Ca(NO3)2 + __NaCl
Example:
__C4H10 + __O2
__CO2 + __H2O
Example:
? 2
__C4H10 + __O
__CO
4
5 2O
2 + __H
13 O
Example:
2
13
__C
H
+
__O
4 10
2
8
10
__CO
+
__H
O
2
2
Example:
Hydrogen + Oxygen  Water
2 2
__H
2 2O
+ __O2  __H
Example:
Aluminum + Oxygen  Aluminum Oxide
4
__Al
2 2O3
3 2  __Al
+ __O