Chemistry 1A
Name: ______________________________________________Your test is on Friday, 12/18/15
Knick
Chemical Reactions Study Guide
Balancing Chemical Equations
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.
Practice: H0w many of each type of atom is represented.
3 Cl2 __6_____
I2 ___2____
Fe ___1____
4 Ni ___4____
2 S8 __16_____ MgF2 _______1 Mg:2F________________
2 Li2O ____4 Li: 2 O__________________ H2O2 _____2 H: 2O_____________
H2SO4 ______2 H: 1 SO4_____________________ 2 Pb(NO3)2 _________2 Pb: 4 NO3______________________
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
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.
____2__H2 + ______O2  ___2___H2O
___16___Na + ______S8  __8____Na2S
___2___NaHCO3  ______Na2CO3 + ______CO2 + ______H2O
____2__Al + ___3___CuO  ______Al2O3 + ___3___Cu
______K2O + ______H2O  ___2___KOH
___6___Mg + ______P4  ____2__Mg3P2
______C2H4 + ____3__O2  ___2___H2O + ___2___CO2
Chemistry 1A
Name: ______________________________________________Your test is on Friday, 12/18/15
Knick
The Five Types of Chemical Reactions
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
Practice: Identify the type of reaction for each of the following reaction equations.
2 C3H6 + 9 O2  6 CO2 + 6 H2O
Type? ____combustion________________________________________
Zn + 2 AgF  2 Ag + ZnF2
Type? ______single______________________________________
H 2O 2  H 2 + O 2
Type? _______decomposition_________________________________
Mg + Cl2  MgCl2
Type? __________synthesis__________________________________
NaCl + AgNO3  NaNO3 + AgCl
Type? _____________double_______________________________
III. Predict the Products
Practice: Determine the products of each reaction. Then balance the equation.
______HCl + ______LiOH  ______HOH_______ + _____LiCl________
______HNO3 + ______NaOH  _____HOH________ + _____NaNO3________
______C2H4 + ____3__O2  _____2_CO2_______ + _______2_H2O__________
____2__Na + ______Cl2  ____2_NaCl________
H2O2  _____H2________ + _____O2________
______Cu + ____2__Ag(NO3)  ________Cu(NO3)2_____ + ____2__Ag_______ (HINT: Cu has a +2 charge)
_____2_Na + ______Cl2  ______2_NaCl______
_____2_HCl + ______Ca  _______H2______ + ________CaCl2__________