Chemical Reactions Notesheet
Name: _____________________________
Applied Chemistry
Date:_______________ Period: _______
A. Mechanics of a Chemical Reactions
1. Chemical Reaction – The type of reaction in which the properties of the _________________
are different from the ____________________.
2. Chemical Change – A change that produces new substances with new ___________________
and ________________________.

Physical changes do __________ change the _________________ of a substance.

Nuclear changes involve changes to the ______________. Ex) fission and fusion
3. Signs that a chemical change or reaction has occurred:
a)
b)
c)
d)
e)
4. Chemical Equation – a description of a chemical reaction using ___________________
instead of ________________.
5. Parts of a Chemical Equation
CH4 + O2  H2O + CO2
reactants
products
a. Reactants
 Written on the _________________ side of the arrow
 ___________________ material in a chemical reaction
b. Products
 Written on the ________________ side of the arrow
 Newly formed substances that are _______________ in a chemical reaction
 Properties are __________________ than those of the reactants.
c. Arrow
 ______________ sign
 Means ___________________
 Separates the __________________ from the ___________________.
d. Plus sign
 Used to _________________ reactants and to _________________ products.
H2 (g) + O2 (g) 
H2O (l)
KI (aq) + PbNO3 (aq)  PbI2 (s) + KNO3 (aq)
e. The following symbols indicate the substance’s physical state:

g:

l:

s:

aq:
(which means dissolved in
)
**The physical states are in parentheses beside the reactant or product.**
Example:
H2 (g) +
Cl2 (g)

HCl (g)
A. What is (are) the reactant(s) in the above equation?
B. What is (are) the products(s) in the above equation?
C. What is the physical state of all the substances?
f. Catalysts are sometimes added to reactants to help _______________ _______ a chemical
reaction.
 Catalysts are __________________ in a chemical reaction. They are neither
reactants nor products.
 Catalysts are written ______________ the yield sign.
MnO2
H2O2 
 H2O + O2
6. Law of Conservation of Mass

Mass is neither
nor
in a chemical reaction, it can only ____________
_____________. Mass of reactants is the
as the mass of the products.

The number of each type of atom in the reactants must be _______________ to the number
of atoms in the ____________________.

Since the number of atoms is the same, the __________________ will be the same on both
sides of the reaction.

Also, the _______________ of element will be the same on each side.
B. Balancing Equations
Look at the following equation:
H2 (g) +
Cl2 (g)

HCl (g)
# of H atoms ________
# of H atoms ________
# of Cl atoms ________
# of Cl atoms ________
Does this equation have the same number of atoms of each element on both sides of the equation?
______________ Therefore, it (does or does not) follow the Law of Conservation of mass.
1. The above equation is called a __________________ equation.
2. The equation must be _____________________ with ________________(the number in front
of a formula for a substance).
H2 (g) + Cl2 (g) → 2HCl (g)
# of H atoms ________
# of H atoms ________
# of Cl atoms ________
# of Cl atoms ________
A coefficient of 1(one) is understood and is not necessary in the balanced chemical equation.
Steps for balancing equations:
1. Write the chemical formula for each reactant and product.
2. Indicate the state of each substance.
3. Use __________________ in front of the substance to balance the equation. The number
of each _______________ should be the ________________ on both sides of the
equation.
NOTE: NEVER CHANGE SUBSCRIPTS!!!
Balance the following equations:
1. _____ H2(g)
+ _____ Br2(g)

_____ HBr(g)
2. _____ Na(s)
+ _____ Cl2(g)

_____ NaCl(s)
3. _____ Na(s)
+ _____ O2(g)

_____ Na2O(s)
4. _____ Zn(s)
+ _____ HCl(aq)

_____ ZnCl2(aq)
5. _____ Fe(s)
+ _____ O2(g)

_____ Fe2O3(s)
6. _____ P4(s)
+ _____ O2(g)

_____ P2O5(s)

_____ Al(s)
7. _____ Al2O3(s)
+ _____ H2(g)
8. _____ Ca(s)
+ _____ O2(g)

_____ CaO(s)
9. _____ Cl2(g)
+ _____ AlBr3(aq)

_____ Br2(l)
10. _____ HgO(s)

_____ Hg(l)
+
+ _____ H2(g)
+
_____ H2O(l)
+ _____ AlCl3(aq)
_____ O2(g)
C. Types of Chemical Reactions
1. Synthesis Reactions
 Two or more reactants produce _____________ product
 A.K.A. __________________ reactions
 Follows the pattern: A + B  AB
** Only ONE product**
Example:
N2(g)
+
3H2(g)
____ reactants

2NH3(g)

____ product
2. Combustion Reactions
 Chemical reaction involving ______________ in which light and heat are produced.
 When fuels are burned in the presence of oxygen, ______________________ and
_______________________ are often produced.
 Follows the pattern: BC + A  BA + CA
Example:
CH4(g) + 2O2(g)

CO2(g) + 2H2O(g)
+ heat energy
3. Decomposition Reactions
 Opposite of _________________________ reactions
 Substance breaks down into _________________________
 Chemists can cause decomposition, but decomposition can also be ______________.
 Follows the pattern:
AB  A + B
** Only ONE reactant**
Example:
2H2O(g)

____ reactant 
2H2(g)
+ O2(g)
____ products
4. Single Displacement (Replacement) Reactions
 Change in __________________________
 One substance will _____________, or _________________, another element in a
compound.
 Follows the pattern:
A + BC  AC + B
**2 reactants (1 element, 1 compound) and 2 products (1 element, 1 compound) **
Example:
Zn
+
H2SO4 
ZnSO4
+
H2(g)
5. Double Displacement (Replacement) Reactions
 Both substances change _____________________
 Follows the pattern:
AB + CD 
AD + CB
**2 reactants (both compounds) and 2 products (both compounds) **
Example:
KI (aq) + PbNO3 (aq)  PbI2 (s) + KNO3 (aq)
D. Reactivity of Metals – SINGLE REPLACEMENT REACTIONS
1. The reactivity of a metal is based on its ability to _________________ another in a compound.
2. If a single replacement reaction occurs, the metal that “cuts in” is ______________ reactive
than the one that was removed.
3. An activity series of metals is a listing that ranks metals according to their _______________.
 The MOST active metal is at the _________ of the list
 The LEAST active metal is at the ____________________ of the list.
4. The activity series is listed below:
lithium
potassium
barium
strontium
calcium
sodium
magnesium
aluminum
manganese
zinc
iron
cadmium
cobalt
nickel
tin
lead
hydrogen
copper
silver
mercury
gold
The most active metal is ________________________.
The least active metal is ________________________.
Which is more active, nickel or iron? ________________________
Al + CuCl2  ______________ + ______________
Mg + HCl  ______________ + ______________
Cu + HCl  __________________________
E. Treatment of Metals
1. Metals are treated to protect from ______________________ or to make the metals better
suited for specific purposes, such as improving ____________________ or making
_________________.
2. Types of Metal Treatments
a.
Galvanizing – _____________________________________________________________
b.
Painting - ________________________________________________________________
c.
Making Alloys – ___________________________________________________________
3. Common Alloys
a.
Bronze – _______________________________________________
b.
Brass –
_______________________________________________
c.
Steel –
_______________________________________________
d.
Stainless Steel - _________________________________________
e.
Pewter – _______________________________________________
f.
Solder – _______________________________________________
F. Energy Changes in Chemical Reactions
1. Exothermic Reactions
 _____________ heat into the surroundings.
o Surrounding will get _________________.

Sometimes need heat to get them started.

A noticeable __________________ in temperature occurs.

Example:
2. Endothermic Reactions
 ____________ heat from the surroundings.
o Surroundings will get _________________.

Need heat to keep them going.

A noticeable __________________ in temperature occurs.

Example: