Chemical Equations Module
Lanisha Davis
5-12-14
1st Period
What Is A Chemical Equation?
 Chemical Equation- a statement that uses chemical
formulas to show the identities and relative amounts
of the substances involved in a chemical reaction.
Parts of an Equation
Reactants
The starting substances, which combine in the
reaction. (Formulas must be correct.)
Products
The substances that are formed by the reaction.
(Formulas must be correct.)
Found between reactants and products, means "reacts
to form."
Used between reactants and products to show that
the equation is not yet balanced.
Placed after the formula of a product that is a gas.
Placed after the formula of a product that is an
insoluble solid, also called a precipitate.
Physical State
Indicates the physical state of the substance whose
formula it follows.
(g) Indicates that the substance is a gas
(l) Indicates that the substance is a liquid
(s) Indicates that the substance is a solid
(aq) Means that the substance is in aqueous (water)
solution
Parts of An Equation
Coefficients
The numbers placed in front of the
formulas to balance the equation.
Conditions
Words or symbols placed over or under
the horizontal arrow to indicate
conditions used to cause the reaction.
Heat is added
hv Light is added
elec Electrical energy is added
Synthesis Reaction
 Reaction in which 2 or more substances react to
produce a single product
 Form A +B
AB
 EX:8 Fe + S8 ---> 8 FeS
Decomposition Reaction
 Occurs when a compound breaks up into the
elements or simpler compounds
 Form AB
A+B
 EX: 2 H2O ---> 2 H2 + O2
Single Replacement Reaction
 Occurs when one element replaces another in a
compound
 Form: A+ BC
AC + B
 EX: Mg + 2 H2O ---> Mg(OH)2 + H2
Double Replacement Reaction
 Occurs when a metal replaces a metal in a compound
and a non metal replaces a non metal in a compound
 Form: AB + CD
AD + CB
 EX: Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3
Combustion Reactions
 Occurs when a hydrocarbon or other elements reacts
with oxygen gas
 Form: C10H8 + 12 O2 ---> 10 CO2 + 4 H2O
Sample Problems & Answers
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1) NaOH + KNO3 --> NaNO3 + KOH
double displacement
2) CH4 + 2 O2 --> CO2 + 2 H2O
combustion
3) 2 Fe + 6 NaBr --> 2 FeBr3 + 6 Na
single displacement
4) CaSO4 + Mg(OH)2 --> Ca(OH)2 + MgSO4
double displacement
5) Pb + O2 --> PbO2
synthesis
6) Na2CO3 --> Na2O + CO2
 decomposition
Balancing Equations
 First to balance equations you have to look at the
equations and see is it already balanced.
 You do this by seeing how many elements there are
on each side of the equation.
 Then make all the same elements equal by using
COEFFIENCTS!
Balancing Video
Video
Video Continue
Balancing Instructions
Finally Balanced