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Types of Reactions
Double Replacements:
Redox Reactions:
Combustions
Decompositions
Reactions can be grouped
into general categories.
Each category follows a
pattern that can be used
to predict the possible
products & outcomes of
the chemical reaction in
question.
Synthesis
Single Replacements
Combustions: Reactions with Oxygen (O2)

Combustion often occurs with hydrocarbons (CxHy) to produce
CO2 & H2O:
Balance Carbon first, Hydrogen second, and Oxygen last.

Other substances can also combust (“burn”) in oxygen.
◦ Write the combustion of Iron metal to product Iron (III) Oxide (aka “rust”)
◦ Write the combustion of Phosphorus (as P4) to form P4O10
iClicker Participation Question:
Combustion of Gasoline
How many oxygen molecules (O2) are needed to
completely react with one molecule of C7H16
(a component of gasoline) to form
A. 7
carbon dioxide and water?
B. 8
C. 11
D. 14
E. 22
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Decomposition Reactions
Decomposition: Starts with one substance and breaks it into many
simpler products.
Consider the following chemical reaction:
2 H2O2 → O2(g) + 2 H2O
Sentence form:
Hydrogen peroxide breaks apart (decomposes) into oxygen
gas and water.
SYNTHESIS
Simple substances combine to form more complex compounds.
Example: Tungesten (IV) carbide can be made by heating Tungsten
metal with Carbon to 1400 oC. Write the balanced chemical equation for
this process.
Example: Write the balanced equation for forming Chlorine Trifluoride
from Chlorine & Fluorine gas.
In an industrial accident, a spill of 900 kg of chlorine trifluoride BURNED
through 12 inches of concrete & almost 3 feet of gravel beneath!
Double Replacement Reactions
Double Replacement: a reaction where two SIMILAR groups
switch positions.
This most often occurs when two ionic compounds react to
form two new compounds by simply trading cations.
In order for a double replacement reaction to actually occur,
one of the products must NOT be aqueous – a PRECIPITATE
must form for the reaction to occur.
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1. PREDICT the products of the double replacement reaction.
2. BALANCE the equation.
3. Use the SOLUBILITY CHART to predict the phase of each
component in the reaction.
3. Use the SOLUBILITY CHART to predict the phase of each
component in the reaction.
1. PREDICT the products of the double replacement reaction.
2. BALANCE the equation.
3. Use the SOLUBILITY GUIDELINES to predict the phase of each
component in the reaction.
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3. Use the SOLUBILITY GUIDELINES to predict the phase of each
component in the reaction.
3. Use the SOLUBILITY CHART to predict the phase of each
component in the reaction.
AFTER mixing the solutions,
but BEFORE any reaction occurs
3. Use the SOLUBILITY CHART to predict the phase of each
component in the reaction.
AFTER reaction occurs &
PRECIPITATE FORMS
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Water treatment
plants often use
precipitate reactions
to remove toxic
heavy metals from a
water supply.
This reduces the level
of dissolved metal
ions to an acceptable
levels by converting
most of the metal to
its insoluble form.
iClicker Participation Question:
Predicting the products of Double Replacement Reactions
What is a possible product from mixing
AgNO3(aq) with Na3PO4(aq)?
A. AgPO4
B. Ag3PO4
C. AgNa3
When the ions switch places, be sure
write the formulas of the products so
that NEUTRAL compounds form (with the
smallest whole number ratio of atoms).
D. NO3PO4
E. Na3NO3
iClicker Participation Question:
General Solubility Guidelines
A. AgOH(s)
Based on the observations below, what is the likely
identity of the precipitate in the first reaction?
AgNO3(aq) + K2Cr2O7(aq) → PRECIPITATE FORMS
HNO3(aq) + KOH(aq) → NO PRECIPITATE FORMS
B. Ag2Cr2O7(s)
C. KNO3(s)
D. H2Cr2O7(s)
E. NO3Cr2O7(s)
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SINGLE Replacement Reactions
Single Replacement: a reaction where one type of element is
replaced with another.
A binary compound (often an ionic compound) reacts with a
substance composed of a single element.
Single replacement reactions are a type of of REDOX
reaction (involving an exchange of electrons)
Batteries make use of Redox reactions: Write the balanced equation
for Zinc metal reacting with copper (II) sulfate to produce zinc (II) sulfate
and copper metal.
In the course of history, the discovery of single reactions has repeatedly
revolutionized human civilizations. The start of the Iron Age around 1300 B.C.
marked the moment we learned to transform brittle iron ores to iron metal.
This affected everything from how we grew food to how we waged wars.
Write the balanced chemical equation describing
iron (III) oxide reacting with carbon atoms to form
iron metal and carbon dioxide.
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Galvanized Steel
Iron metal corrodes in the presences of oxygen and water to produce rust
(Fe2O3), which compromises the strength of the metal. Galvanized steel
uses a barrier of zinc or magnesium metal to protect the iron from
corrosion.
Write the balanced equation for magnesium
metal reacting with Iron (III) Oxide (aka “rust”)
to produce Iron metal & magnesium oxide.
Stoichiometry:
Studying the quantities in chemical reactions
Law of Conservation of Mass: requires the same number
of atoms on each side of the chemical equation.

Helpful in predicting the amount of
products that can form based on the
amount of starting reactants
2 NaN3(s)

2 Na(s) + 3 N2(g)
2 sodium azide units will decompose
into just 2 sodium atoms & 3
nitrogen molecules.
Sodium azide decomposition is
used to inflate air bags.
Mole-to-Mole Conversions:
Stoichiometric coefficients express PARTICLE ratios
2 NaN3(s)
2 Na(s) + 3 N2(g)
How many moles of N2 could form from 6 moles of NaN3?
Theoretical Yield: MAXIMUM amount of product that can form
in a reaction based on the limited starting materials.
How many moles of NaN3 are needed to produce 2.67 moles of N2 gas
(about the amount of gas needed to fill one airbag)?
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iClicker Participation Question:
Mole-to-Mole Conversions—From Reactants to Products
How much NH3 could be produced, if 40 moles of hydrogen
gas react with ample nitrogen gas according
to the equation below?
A. 80 moles
N2(g) + 3 H2(g)
B. 60 moles
C. 40 moles
2 NH3(g)
“The expansion of the world's population
from 1.6 billion people in 1900 to today's
seven billion [in 2012] would not have been
possible without the [industrial] synthesis
of ammonia.“ –MIT Press
D. 27 moles
E. 20 moles
Mass-to-Mass Conversions:
How many grams of sodium metal can be produced from the
decomposition of 130 grams of sodium azide?
# of grams
NaN3
2 NaN3(s)
# of grams
Na
2 Na(s) + 3 N2(g)
Moles cannot be measured directly, but…
Molar Mass
of NaN3:
22.99 +
3 x 14.01 =
65.02 g/mol
MASS can be measured on a balance &
tied to the number of moles with
MOLAR MASS
Mole-to-mole ratios relate
reactants & products:
# of moles
NaN3
2 NaN3 produce 2 Na
Molar Mass
Na:
22.99 g/mol
# of moles
Na
What volume of water could form from the
combustion of 20. mL of C3H8O?
2 C3H8O + 9 O2(g)
# of moles
C3H8O
2 mol of C3H8O
make 8 mol H2O
MOLAR MASS = 60.1 g/mol
Mass of
C3H8O
DENSITY = 0.786 g/mL
Volume of
C3H8O
6 CO2(g) + 8 H2O(g)
# of moles
H2O
MOLAR MASS = 18.0 g/mol
Mass of
H2O
DENSITY = 1.00 g/mL
Volume of
H2O
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Limiting Reagents:
2 C3H8O + 9 O2(g)
6 CO2(g) + 8 H2O(g)
Trial 2:
Trial 1:
• For the reaction to occur, C3H8O
must combine with O2 in a 2 to
9 ratio
• 20 mL C3H8O reacts O2 in bottle
to produce CO2, H2O, & HEAT
•
•
•
Without
NO REACTION
2, there isReagent:
O2 is theOLimiting
It
Inside the
O2 isofdepleted
LIMITS
thebottle:
amount
product
Reaction is LIMITED to the
that can form. The other
opening where O2 is present
reactant is in EXCESS.
How many grams of oxygen would be needed to
completely react with 20. mL of C3H8O?
2 C3H8O
# of moles
C3H8O
9 O2(g)
2 mol of C3H8O
react with 9 mol O2
MOLAR MASS = 60.1 g/mol
Mass of
C3H8O
+
# of moles
O2
MOLAR MASS = 32.0 g/mol
Mass of
O2
DENSITY = 0.786 g/mL With LESS than 38 g O : the 20 mL of
2
C3H8O cannot fully react. This would
Volume of
make the O2 the limiting reagent &
C3H8O
the C3H8O would be in excess.
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