10/5/2013


Today:
◦ Chemical Reactions:




Combustions

Decompositions
Synthesis Reactions
Double Replacement Reactions
 Precipitations & Solubility Rules
 Acid-Base Reactions
 Single Replacement Reactions:
Course Survey 2:
◦ Complete by 11 pm tonight, and
receive 5 points extra credit
Next Meeting
◦ Concept Check:
 Covers today’s material
◦ Reading: Chp. 8, pp. 249-271
◦ Next Week in Lab:
 Standard Quiz 2: Covers Lectures 8 & 9
on Empirical & Molecular Formulas,
Balancing Equations & Classes of
Chemical Reactions
 See CANVAS for a checklist of topics to
be covered
“The only thing constant in life is CHANGE.”
—François de la Rochefoucauld
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10/5/2013
Types of Reactions
Combustion
Decomposition
Synthesis
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.
Double Replacement
Single Replacement
Graded Concept Check:
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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10/5/2013
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
A Combustion without the formation of CO2
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10/5/2013
Combustion of Elemental Sulfur

Write the balanced equation for the combustion of Sulfur (S8) to
produce Sulfur Trioxide.
Burning Sulfur (aka “brimstone” as in “fire and brimstone”)
has been used as a fumigant to kill pests due to the toxicity of
the sulfur oxides.
Types of Reactions
Combustion
Decomposition
Synthesis
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.
Double Replacement
Single Replacement
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10/5/2013
Decomposition: From One to Many

A single substance breaks into multiple simpler substances
◦ Some decompositions are SPONTANEOUS.
 Example: Hydrogen peroxide decomposes to oxygen gas and water
 Example: Carbonic acid (H2CO3) decomposes
to carbon dioxide gas & water
◦ Others decompositions require heat, light
or electrical current to occur.
 Example: Water can be forced to break into its
component elements through electrolysis
(decomposition from electricity)
Thermal Decomposition:
Breaking a substance down with thermal energy
Write the balanced equation for the decomposition of mercury (II)
oxide to produce mercury metal & oxygen gas
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10/5/2013
Types of Reactions
Combustion
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.
Decomposition
Synthesis
Double Replacement
Single Replacement
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!
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10/5/2013
SYNTHESIS
Sodium Chloride can be synthesized from sodium metal & chlorine gas:
Types of Reactions
Combustion
Decomposition
Synthesis
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.
Double Replacement
Single Replacement
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10/5/2013
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.
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.
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10/5/2013
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.
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10/5/2013
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.
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10/5/2013
3. Use the SOLUBILITY CHART to predict the phase of each
component in the reaction.
AFTER reaction occurs &
PRECIPITATE FORMS
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.
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10/5/2013
Solubility Chart
Anions
Soluble (aq)
Precipitate (s)
nitrate
Most cations
No common cations
acetate
Most cations
Ag+
fluoride
chloride
bromide
iodide
Most cations
Ag+, Pb2+,4+, Hg22+, Tl+
sulfate
Most cations
Ba2+, Sr2+,Pb2+,4+, Ag+,Ca2+
chromate
Most cations
Ba2+, Sr2+, Pb2+,4+, Ag+
sulfide
hydroxide
oxide
NH4+ & Cations of columns
1 and 2
Most other cations
carbonate
phosphate
NH4+ & Cations of column 1
EXCEPT Li+
Most other cations
Evaluate the solubility of the
possible products:
• Sodium Iodide is soluble.
• Potassium Chloride (KCl) is
soluble.
Therefore NO REACTION occurs.
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10/5/2013
iClicker Question:
Predicting the products of Double Replacement Reactions
What is a possible product from mixing AgNO3(aq) with
Na2SO4(aq)?
A. AgSO4
B. Ag2SO4
C. AgNa2
D. NO3SO4
E. Na2NO3
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).
More Examples
Acid-Base Reactions are also Double Replacements:
Driving force is the formation of water or a gas
Hydrogen ions exchange places with a metal
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10/5/2013
Types of Reactions
Combustion
Decomposition
Synthesis
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.
Double Replacement
Single Replacement
SINGLE Replacement Reactions
Single Replacement: a reaction where one type of element is
replaced with another.
This most often occurs when 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.
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10/5/2013
Galvanized Steel
Iron metal corrodes in the presences of oxygen and water to produce
rust. Galvanized steel uses a barrier of Zinc metal to protect the iron from
corrosion.
Write the balanced equation for Zinc metal reacting with Iron (III) Oxide
(aka “rust”) to produce Iron metal & Zinc (II) Oxide.
Single Replacement Reaction: A Particle View
Copper
wire
Silver
nitrate
solution
+1
–1
0
2AgNO3(aq) + Cu(s)
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10/5/2013
Single Replacement Reaction: A Particle View
Copper
wire
Silver
nitrate
solution
Cu2+
Ag+
Ag+
2e–
Ag atoms
coating
wire
Cu atoms
in wire
+1
–1
0
2AgNO3(aq) + Cu(s)
Single Replacement Reaction: A Particle View
Copper
wire
Silver
nitrate
solution
Cu2+
Ag+
Ag+
2e–
Ag atoms
coating
wire
Cu atoms
in wire
+1
–1
0
2AgNO3(aq) + Cu(s)
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10/5/2013
Single Replacement Reaction: A Particle View
Copper wire
coated with
silver
Copper
wire
Copper
nitrate
solution
Silver
nitrate
solution
Cu2+
Ag+
Ag+
2e–
Ag atoms
coating
wire
Cu atoms
in wire
+1
–1
0
+2
2AgNO3(aq) + Cu(s)
–1
0
Cu(NO3)2(aq) + 2Ag(s)
Single Replacement Reaction: A Particle View
Copper wire
coated with
silver
Copper
wire
Copper
nitrate
solution
Silver
nitrate
solution
Cu2+
Ag+
Ag+
2e–
Ag atoms
coating
wire
Cu atoms
in wire
+1
–1
0
2AgNO3(aq) + Cu(s)
+2
–1
0
Cu(NO3)2(aq) + 2Ag(s)
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10/5/2013
Types of Reactions
Combustion
Decomposition
Synthesis
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.
Double Replacement
Single Replacement
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