Name:____________________________
Date:______________ Per #:________
Chemical Reactions Study Guide
I. Balancing Chemical Equations
Notes
#5
The first step to balancing chemical reaction equations is to be able to accurately count the number of
each type of element on both the reactants and products side of the arrow. This is done by multiplying the
coefficient (big number in front of an element symbol) with the subscript (little number found after the
element symbol). Remember: if no coefficient or subscript is written, then there is an implied, imaginary “1”.
Examples: 3 Br2  there are 6 bromine atoms (3  2 = 6)
CaO  there is 1 calcium and 1 oxygen (in each case 1  1 = 1) The “1”s are implied.
CH4 + O2  H2O + CO2  There are 3 total oxygens on the product (right) side (1  1 + 1 2 = 3)
Practice: H0w many of each type of atom is represented.
3 Cl2 _______
I2 _______
Fe _______
4 Ni _______
MgF2 _______________________
2 Li2O ______________________ H2O2 _______________________
H2SO4 ________________________________
C2H4 + O2  H2O + CO2
2 S8 _______
2 Pb(NO3)2 _________________________________
Reactants _________________________________________________
Products _________________________________________________
Notes
#6
Now that we’ve learned to count, it’s time to put our skills into action by altering the numbers of
certain elements to suit our desires. In any case, our desires are to have the same number of each type of
element on both the products and reactants side of the equation. We do this by changing the coefficients.
Example: Li + O2  Li2O
A lovely synthesis reaction. What do we do first?
1. Count the number of each element on both sides.
Reactants: 1 Li and 2 O’s
Products: 2 Li’s and 1 O
2. Add/change coefficients to balance.
1) First, I check the first element, Li (lithium). There’s one on the reactants side and 2 on the
products, so I’ll add a coefficient of 2 to the reactants to balance: 2 Li + O2  Li2O
2) Now for O (oxygen). 2 on reactants, 1 on product so I’ll put a 2 in front of Li 2O to balance:
2 Li + O2  2 Li2O
3) Whoops, that affects lithium. I now have four on the products side, so I’ll go back and change
the “2” to a “4” on the reactants side: 4 Li + O2  2 Li2O
BALANCED!!!! 
Practice: Balance each of the following chemical reaction equations. Check your answer by counting each
element on each side when you think you’re done.
______H2 + ______O2  ______H2O
______Na + ______S8  ______Na2S
______NaHCO3  ______Na2CO3 + ______CO2 + ______H2O
______Al + ______CuO  ______Al2O3 + ______Cu
______K2O + ______H2O  ______KOH
______C2H4 + ______O2  ______H2O + ______CO2
______Mg + ______P4  ______Mg3P2
Name:____________________________
Date:______________ Per #:________
II. The Five Types of Chemical Reactions
Notes
#7, 8
This should be pretty simple. All you need to do is remember the names of the 5 types of rxns and the
“Key to recognizing” each of them. As long as you understand what the symbols in a chemical reaction mean,
it should be pretty simple.
1. Synthesis: Key = 2 reactants  1 product
2. Decomposition: Key = 1 reactant  2 products
3. Combustion: Key = products are only H2O and CO2
4. Single displacement: Key = there is a lonely (non-bonded) metal element on each side
5. Double displacement: Key = 2 ions switch places
Examples:
2 K + F2  2 KF
This is synthesis because two different reactants combine to make
one product.
2 NaOH + CuSO4  Na2SO4 + Cu(OH)2
This is double displacement because the SO4 and
OH ions switch places.
Practice: Identify the type of reaction for each of the following reaction equations.
2 C3H6 + 9 O2  6 CO2 + 6 H2O
Type? ____________________________________________
Zn + 2 AgF  2 Ag + ZnF2
Type? ____________________________________________
H 2O 2  H 2 + O 2
Type? ____________________________________________
Mg + Cl2  MgCl2
Type? ____________________________________________
NaCl + AgNO3  NaNO3 + AgCl
Type? ____________________________________________
III. Acid and Base Chemistry
Note
s
#9
There will be questions (multiple choice and otherwise) about the properties of acids and bases, i.e.
their characteristics, pH ranges, the ions they produce when they dissolve in water, and the difference
between strong and weak acids/bases. Study your notes for that stuff. The main free response stuff you’ll
need to know is neutralization reactions. They are easy, there are 2 things you need to remember.
1) Neutralization reactions are a form of double displacement.
2) The products of neutralization reactions are always water and a salt.
Example:
HI + KOH  H2O + KI
Practice: Determine the products of each neutralization reaction. Then balance the equation.
______HCl + ______LiOH  _____________ + _____________
______HNO3 + ______NaOH  _____________ + _____________
______H2SO4 + ______KOH  _____________ + __________________
______HBr + ______Ba(OH)2  _____________ + _____________