Chemical Reactions: Key Concepts and Practice Problems
Chapter 11:
Chemical
Reactions
Jennie L. Borders
Section 11.1 – Describing
Chemical Reactions
In a chemical reaction, the
reactants
are
written on the
left
and the
products
on
the
right
.
The
arrow
that separates them is called
yield
.
Reactants
Products
Symbols in Equations
Pt
Catalyst
A
catalyst
is a substance that
speeds
up a
reaction but is not
used up
in the
reaction.
A
catalyst
is neither a
reactant
nor a
product
, so its formula is written
above
the
arrow
in a chemical equation.
Word Equations
To write a
word equation
, write the names
of the reactants and products in a
sentence form
.
Ex: chemical equation
2H
2(g)
+
O
2(g)
2H
2
O
(l)
Ex: word equation
Hydrogen gas
and
oxygen gas
react to
form
liquid water
.
Sample Problem #1
Write a sentence that describes this
chemical reaction:
Na
(s)
+
H
2
O
(l)
NaOH
(aq)
+
H
2(g)
Solid sodium
and
liquid water
react to
form
aqueous sodium hydroxide
and
hydrogen gas
.
Practice Problem #1
Write a sentence that describes this
reaction:
H
2
SO
4(aq)
+ BaCl
2(aq)
BaSO
4(s)
+ HCl
(aq)
Aqueous sulfuric acid and aqueous barium chloride
react to form solid barium sulfate and aqueous
hydrochloric acid.
Sample Problem #2
Write the chemical equation for the
following reaction:
Hydrochloric acid
and
solid sodium
hydrogen carbonate
react to produce
aqueous sodium chloride
,
water
, and
carbon dioxide
.
Hint:
Acids
will always be
aqueous
unless
otherwise stated.
HCl
(aq)
+
NaHCO
3(s)
NaCl
(aq)
+
H
2
O
(l)
+
CO
2(g)
Practice Problem #2
Write the chemical equation for the
following reaction:
Solid iron(III)hydroxide is heated to form
solid iron(III)oxide and water
Fe(OH)
3(s)
Fe
2
O
3(s)
+ H
2
O
(l)
Balancing Chemical Equations
2
H
2
(
g)
+ O
2
(g)
2
H
2
O
(l)
o
Coefficients
are the numbers
in front
of a
chemical formula.
o
Subscripts
are numbers that show the number of
atoms
in a compound.
o
When balancing reactions, you can only
change the
coefficients
,
not
the
subscripts
.
o
A
skeleton equation
is an equation that has no
coefficients
.
Balancing Chemical Equations
To balance a chemical equation, you
add
coefficients
to the substances so that
the reactant and product side of the
equation contain
equals numbers and
types of atoms
.
Coefficients
are added so that the
equation follows the
law of conservation
of mass
.
Rules for Balancing Equations
Balance
hydrogen
and
oxygen
last.
Count a
polyatomic ion
as a single unit if it
appears
unchanged
on both sides of the
equation.
If you end up with an
odd number
, you
can
double
all of the coefficients.
Make sure to
reduce
the coefficients to
the
lowest whole-number ratio
.
A coefficient of
one
is understood and
does not need to be
written
.
Sample Problems
Balance the following equations:
1.
___H
2
+ ___O
2
___H
2
O
2.
___AgNO
3
+ ___H
2
S
___Ag
2
S + ___HNO
3
3.
___Zn(OH)
2
+ ___H
3
PO
4
___Zn
3
(PO
4
)
2
+ ___H
2
O
2
H
2
+ ___O
2
2
H
2
O
2
AgNO
3
+ ___H
2
S
___Ag
2
S +
2
HNO
3
3
Zn(OH)
2
+
2
H
3
PO
4
___Zn
3
(PO
4
)
2
+
6
H
2
O
Practice Problems
1.
___FeCl
3
+ ___NaOH
___Fe(OH)
3
+ ___NaCl
2.
___CS
2
+ ___Cl
2
___CCl
4
+ ___S
2
Cl
2
3.
___C
2
H
6
+ ___O
2
___CO
2
+ ___H
2
O
___FeCl
3
+
3
NaOH
___Fe(OH)
3
+
3
NaCl
___CS
2
+
3
Cl
2
___CCl
4
+ ___S
2
Cl
2
2
C
2
H
6
+
7
O
2
4
CO
2
+
6
H
2
O
Section 11.1 Assessment
1.
Describe the steps in writing a balanced
chemical equation.
2.
Write the skeleton equation for the following
reactions:
a.
Heating solid copper(II)sulfide in the presence of
oxygen gas produces pure copper and sulfur
dioxide gas.
b.
Iron metal and chlorine gas react to form solid
iron(III)chloride.
CuS
(s)
+ O
2(g)
Cu
(s)
+ SO
2(g)
Fe
(s)
+ Cl
2(g)
FeCl
3(s)
Section 11.1 Assessment
c.
Solid aluminum carbonate decomposes
to form solid aluminum oxide and carbon
dioxide gas.
d.
Solid magnesium reacts with aqueous
silver(I)nitrate to form solid silver and
aqueous magnesium nitrate.
Al
2
(CO
3
)
3(s)
Al
2
O
3(s)
+ CO
2(g)
Mg
(s)
+ AgNO
3(aq)
Ag
(s)
+ Mg(NO
3
)
2(aq)
Section 11.1 Assessment
3.
Balance the following equations:
a.
___SO
2
+ ___O
2
___SO
3
b.
___Fe
2
O
3
+ ___H
2
___Fe + ___H
2
O
c.
___P + ___O
2
___P
4
O
10
d.
___Al + ___N
2
___AlN
2
2
2
2
2
3
3
4
5
Section 11.2 – Types of
Chemical Reactions
The five general types of reactions are
synthesis, decomposition, single
displacement, double displacement, and
combustion
.
Synthesis Reactions
In a
synthesis
reaction, two or more
substances
react to form
one
product.
Generic Reaction:
A + B
AB
Actual Example:
2Mg + O
2
2MgO
Predicting Products
Predict the products for the following
reactions:
1.
Cu + S
(Hint: copper is +1)
2.
Be + O
2
3.
Fe + S
(Hint: iron is +3)
2Cu + S
Cu
2
S
2Be + O
2
2BeO
2Fe + 3S
Fe
2
S
3
Decomposition Reactions
A
decomposition
reaction occurs when a
single
reactant breaks down into two or
more
products
.
Generic Reaction:
AB
A + B
Actual Example:
2HgO
2Hg + O
2
Predicting Products
Predict the products for the following
reactions:
1.
H
2
O
2.
HI
3.
NH
3
2H
2
O
2H
2
+ O
2
2HI
H
2
+ I
2
2NH
3
N
2
+ 3H
2
Single Displacement Reactions
A
single displacement
reaction occurs
when
one
element replaces a second
element
in a compound.
Generic Reaction:
A + BC
B + AC
Actual Example:
Zn + Cu(NO
3
)
2
Cu + Zn(NO
3
)
2
Predicting Products
Predict the products for the following
reactions:
1.
Br
2
+ NaI
2.
Fe + Pb(NO
3
)
2
(Hint: iron is +3)
3.
Zn + H
2
SO
4
(Hint: zinc is +2)
Br
2
+ 2NaI
2NaBr + I
2
2Fe + 3Pb(NO
3
)
2
2Fe(NO
3
)
3
+ 3Pb
Zn + H
2
SO
4
ZnSO
4
+ H
2
Double Displacement
Reactions
A
double displacement
reaction involves
the exchange of
two positive ions
between two compounds.
Generic Reaction:
AB + CD
AD + CB
Actual Example:
2NaCN + H
2
SO
4
2HCN + Na
2
SO
4
Predicting Products
Predict the products for the following
reactions:
1.
CaBr
2
+ AgNO
3
2.
FeS + HCl
3.
NaOH + Fe(NO
3
)
3
CaBr
2
+ 2AgNO
3
2AgBr + Ca(NO
3
)
2
FeS + 2HCl
FeCl
2
+ H
2
S
3NaOH + Fe(NO
3
)
3
Fe(OH)
3
+ 3NaNO
3
Relationships and Reactions
Combustion Reactions
A
combustion
reaction occurs when a
substance burns in
oxygen
and produces
a lot of
heat and light
.
Generic Reaction:
C
x
H
y
+ O
2
CO
2
+ H
2
O
Actual Example:
2C
8
H
18
+ 25O
2
16CO
2
+ 18H
2
O
Predicting Products
Predict the products for the following
reactions:
1.
C
6
H
6
+ O
2
2.
C
7
H
16
+ O
2
3.
C
6
H
12
O
6
+ O
2
2C
6
H
6
+ 15O
2
12CO
2
+ 6H
2
O
C
7
H
16
+ 11O
2
7CO
2
+ 8H
2
O
C
6
H
12
O
6
+ 6O
2
6CO
2
+ 6H
2
O
Section 11.2 Assessment
1.
What are the five types of chemical
reactions?
2.
Classify the following skeleton reactions:
a.
C
3
H
6
+ O
2
CO
2
+ H
2
O
b.
Al(OH)
3
Al
2
O
3
+ H
2
O
c.
Li + O
2
Li
2
O
d.
Zn + AgNO
3
Ag + Zn(NO
3
)
2
Section 11.2 Assessment
1.
Complete and balance each equation:
a.
CaI
2
+ Hg(NO
3
)
2
b.
Al + Cl
2
c.
Ag + HCl
(Hint: silver is +1)
d.
C
2
H
2
+ O
2
e.
MgCl
2
CaI
2
+ Hg(NO
3
)
2
Ca(NO
3
)
2
+ HgI
2
2Al + 3Cl
2
2AlCl
3
2Ag + 2HCl
H
2
+ 2AgCl
2C
2
H
2
+ 5O
2
4CO
2
+ 2H
2
O
MgCl
2
Mg + Cl
2
Section 11.3 – Reactions in
Aqueous Solution
A
complete ionic equation
is an equation
that shows
dissolved
ionic compounds as
dissociated
free ions
.
A
spectator ion
is an ion that is not directly
involved in a
reaction
.
Compounds that are
aqueous
will break
into
ions
, and compounds that are
solid
will remain
bonded
.
Aqueous Ions
When a compound is
aqueous
it breaks
into its
ions
.
Ex:
NaCl =
MgBr
2
=
Al
2
O
3
=
LiNO
3
=
K
2
CO
3
=
Sr(NO
2
)
2
=
Na
+
and Cl
-
Mg
+2
and 2Br
-
2Al
+3
and 3O
-2
Li
+
and NO
3
-
2K
+
and CO
3
-2
Sr
+2
and 2NO
2
-
Rules for Writing Complete
Ionic Equations
1.
Balance
the equation.
2.
Separate
all aqueous substances into
ions
.
3.
Leave any non-aqueous substances or
precipitates
together.
Complete Ionic Equations
Regular Equation:
AgNO
3(aq)
+ NaCl
(aq)
AgCl
(s)
+ NaNO
3(aq)
Complete Ionic Equation:
Ag
+
(aq)
+ NO
3
-
(aq)
+ Na
+
(aq)
+ Cl
-
(aq)
AgCl
(s)
+ Na
+
(aq)
+ NO
3
-
(aq)
Sample Problem
Write the complete ionic equation for the
following reaction:
FeCl
3(aq)
+ KOH
(aq)
Fe(OH)
3(s)
+ KCl
(aq)
First balance the equation:
FeCl
3(aq)
+
3
KOH
(aq)
Fe(OH)
3(s)
+
3
KCl
(aq)
Then write the complete ionic equation:
Fe
+3
(aq)
+ 3Cl
-
(aq)
+ 3K
+
(aq)
+ 3OH
-
(aq)
Fe(OH)
3(s)
+ 3K
+
(aq)
+ 3Cl
-
(aq)
Practice Problems
Write the complete ionic equation for the
following reaction:
NaOH
(aq)
+ Fe(NO
3
)
3(aq)
Fe(OH)
3(s)
+ NaNO
3(aq)
First balance the equation:
3
NaOH
(aq)
+ Fe(NO
3
)
3(aq)
Fe(OH)
3(s)
+
3
NaNO
3(aq)
Then write the complete ionic equation:
3Na
+
(aq)
+ 3OH
-
(aq)
+ Fe
+3
(aq)
+ 3NO
3
-
(aq)
Fe(OH)
3(s)
+ 3Na
+
(aq)
+ 3NO
3
-
(aq)
Net Ionic Equations
A
net ionic equation
shows only those particles
involved in the
reaction
.
The
spectator ions
have been removed.
Ex: complete ionic equation
3Na
+
(aq)
+ 3OH
-
(aq)
+ Fe
+3
(aq)
+ 3NO
3
-
(aq)
Fe(OH)
3(s)
+
3Na
+
(aq)
+ 3NO
3
-
(aq)
When the spectator ions are removed, you are left
with the
net ionic equation
:
Fe
+3
(aq)
+ 3OH
-
(aq)
Fe(OH)
3(s)
X
X
X
X
Sample Problems
To write a
net ionic equation
, you only consider
non-aqueous substances
and the ions that form
them.
Bi(NO
3
)
3(aq)
+ H
2
S
(aq)
Bi
2
S
3(s)
+ HNO
3(aq)
First, balance the equation:
2
Bi
(NO
3
)
3(aq)
+ 3H
2
S
(aq)
Bi
2
S
3(s)
+ 6HNO
3(aq)
Write only the ions involved in the reaction:
2Bi
+3
(aq)
+ 3S
-2
(aq)
Bi
2
S
3(s)
Practice Problems
1.
Write the net ionic equation for the following
reaction:
Pb(NO
3
)
2(aq)
+ H
2
SO
4(aq)
PbSO
4(s)
+ HNO
3(aq)
First balance the equation:
Pb
(NO
3
)
2(aq)
+ H
2
SO
4
(aq)
PbSO
4(s)
+
2
HNO
3(aq)
Write the net ionic equation:
Pb
+2
(aq)
+ SO
4
-2
(aq)
PbSO
4(s)
Practice Problems
Write the net ionic equation for the following
equation:
Na
3
PO
4(aq)
+ FeCl
3(aq)
NaCl
(aq)
+ FePO
4(s)
First, balance the equation:
Na
3
PO
4
(aq)
+
Fe
Cl
3(aq)
3
NaCl
(aq)
+
FePO
4(s)
Write the net ionic equation:
PO4
-3
(aq)
+ Fe
+3
(aq)
FePO
4(s)
Predicting Precipitates
You can predict whether a
precipitate
forms by
using
solubility rules
.
If a substance is
soluble
, then it will dissolve in
water and be
aqueous
.
If a substance is
insoluble
, then it will bond with
another ion and will be a
solid
.
Solubility Rules
Soluble or Insoluble?
If any part of a compound is
soluble
, then
the compound will be
soluble
.
NH
4
Cl
BaSO
4
Na
2
SO
4
Ca(OH)
2
K
3
PO
4
Mg(NO
3
)
2
AgCl
NiCrO
4
Soluble/Aqueous
Soluble/Aqueous
Soluble/Aqueous
Soluble/Aqueous
Insoluble/Solid
Insoluble/Solid
Insoluble/Solid
Insoluble/Solid
Predicting Precipitates
Rules for Predicting Precipitates
1.
Switch the
ions
and balance the
charges
to form the products.
2.
Balance
the equation.
3.
Identify whether the products are
solid or
aqueous
.
Sample Problem
Predict the products for the following
reaction:
HCl
(aq)
+ AgNO
3(aq)
First, form the products:
HCl
(aq)
+ AgNO
3(aq)
HNO
3
+ AgCl
Then, balance the equation:
HCl
(aq)
+ AgNO
3(aq)
HNO
3
+ AgCl
Finally, list states of matter:
HCl
(aq)
+ AgNO
3(aq)
HNO
3
(aq)
+ AgCl
(s)
Practice Problems
1. Predict the products for the following
reaction:
Pb(C
2
H
3
O
2
)
2(aq)
+ LiCl
(aq)
First, form the products:
Pb(C
2
H
3
O
2
)
2(aq)
+ LiCl
(aq)
PbCl
2
+ LiC
2
H
3
O
2
Then, balance the equation:
Pb(C
2
H
3
O
2
)
2(aq)
+
2
LiCl
(aq)
PbCl
2
+
2
LiC
2
H
3
O
2
Finally, list states of matter:
Pb(C
2
H
3
O
2
)
2(aq)
+ 2LiCl
(aq)
PbCl
2
(s)
+ 2LiC
2
H
3
O
2
(aq)
Practice Problems
2. Predict the products for the following
reaction:
NH
4
Cl
(aq)
+ Ba(NO
3
)
2(aq)
First, form the products:
NH
4
Cl
(aq)
+ Ba(NO
3
)
2(aq)
NH
4
NO
3
+ BaCl
2
Then, balance the equation:
2
NH
4
Cl
(aq)
+ Ba(NO
3
)
2(aq)
2
NH
4
NO
3
+ BaCl
2
Finally, list the states of matter:
2NH
4
Cl
(aq)
+ Ba(NO
3
)
2(aq)
2NH
4
NO
3
(aq)
+ BaCl
2
(aq)
Section 11.3 Assessment
1.
What is a net ionic equation?
2.
How can you predict the formation of a
precipitate in a double displacement reaction?
3.
Write the net ionic equation for the following
reactions:
a.
Pb(C
2
H
3
O
2
)
2(aq)
+ HCl
(aq)
PbCl
2(s)
+ HC
2
H
3
O
2(aq)
b.
(NH
4
)
2
S
(aq)
+ Co(NO
3
)
2(aq)
CoS
(s)
+ NH
4
NO
3(aq)
Pb(C
2
H
3
O
2
)
2(aq)
+ 2HCl
(aq)
PbCl
2(s)
+ 2HC
2
H
3
O
2(aq)
Pb
+2
(aq)
+ 2Cl
-
(aq)
PbCl
2(s)
(NH
4
)
2
S
(aq)
+ Co(NO
3
)
2(aq)
CoS
(s)
+ 2NH
4
NO
3(aq)
Co
+2
(aq)
+ S
-2
(aq)
CoS
(s)
Section 11.3 Assessment
4. Predict the products for the following
reactions:
a.
Na
3
PO
4(aq)
+ CrCl
3(aq)
b.
Al
2
(SO
4
)
3(aq)
+ NH
4
OH
(aq)
Na
3
PO
4(aq)
+ CrCl
3(aq)
3NaCl
(aq)
+ CrPO
4(s)
Al
2
(SO
4
)
3(aq)
+ 6NH
4
OH
(aq)
2Al(OH)
3(s)
+ 3(NH
4
)
2
SO
4(aq)
THE END!!
Explore the fundamental concepts of chemical reactions, including how reactants and products are represented, the role of catalysts, and writing word equations. Learn through sample and practice problems illustrating different types of reactions. Master writing chemical equations for reactions involving various substances like sodium, water, acids, and solid compounds.
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Presentation Transcript
Chapter 11: Chemical Reactions Jennie L. Borders
Section 11.1 Describing Chemical Reactions In a chemical reaction, the reactants are written on the left and the products on the right. The arrow that separates them is called yield. Reactants Products
Symbols in Equations Symbol " D (s) (l) (g) (aq) " " Meaning yields reversible reaction solid liquid gas aqueous catalyst heat Pt
Catalyst A catalyst is a substance that speeds up a reaction but is not used up in the reaction. A catalyst is neither a reactant nor a product, so its formula is written above the arrow in a chemical equation.
Word Equations To write a word equation, write the names of the reactants and products in a sentence form. Ex: chemical equation 2H2(g) + O2(g) 2H2O(l) Ex: word equation Hydrogen gas and oxygen gas react to form liquid water.
Sample Problem #1 Write a sentence that describes this chemical reaction: Na(s) + H2O(l) NaOH(aq) + H2(g) Solid sodium and liquid water react to form aqueous sodium hydroxide and hydrogen gas.
Practice Problem #1 Write a sentence that describes this reaction: H2SO4(aq) + BaCl2(aq) BaSO4(s) + HCl(aq) Aqueous sulfuric acid and aqueous barium chloride react to form solid barium sulfate and aqueous hydrochloric acid.
Sample Problem #2 Write the chemical equation for the following reaction: Hydrochloric acid and solid sodium hydrogen carbonate react to produce aqueous sodium chloride, water, and carbon dioxide. HCl(aq) + NaHCO3(s) NaCl(aq) + H2O(l) + CO2(g) Hint: Acids will always be aqueous unless otherwise stated.
Practice Problem #2 Write the chemical equation for the following reaction: Solid iron(III)hydroxide is heated to form solid iron(III)oxide and water D Fe(OH)3(s) Fe2O3(s) + H2O(l)
Balancing Chemical Equations 2H2(g) + O2(g) 2H2O(l) o Coefficients are the numbers in front of a chemical formula. o Subscripts are numbers that show the number of atoms in a compound. o When balancing reactions, you can only change the coefficients, not the subscripts. o A skeleton equation is an equation that has no coefficients.
Balancing Chemical Equations To balance a chemical equation, you add coefficients to the substances so that the reactant and product side of the equation contain equals numbers and types of atoms. Coefficients are added so that the equation follows the law of conservation of mass.
Rules for Balancing Equations Balance hydrogen and oxygen last. Count a polyatomic ion as a single unit if it appears unchanged on both sides of the equation. If you end up with an odd number, you can double all of the coefficients. Make sure to reduce the coefficients to the lowest whole-number ratio. A coefficient of one is understood and does not need to be written.
Sample Problems Balance the following equations: 1. ___H2 + ___O2 ___H2O 2 H2 + ___O2 2 H2O 2. ___AgNO3 + ___H2S ___Ag2S + ___HNO3 2 AgNO3 + ___H2S ___Ag2S + 2 HNO3 3. ___Zn(OH)2 + ___H3PO4 ___Zn3(PO4)2 + ___H2O 3 Zn(OH)2 + 2 H3PO4 ___Zn3(PO4)2 + 6 H2O
Practice Problems 1. ___FeCl3 + ___NaOH ___Fe(OH)3 + ___NaCl ___FeCl3 + 3 NaOH ___Fe(OH)3 + 3 NaCl 2. ___CS2 + ___Cl2 ___CCl4 + ___S2Cl2 ___CS2 + 3 Cl2 ___CCl4 + ___S2Cl2 3. ___C2H6 + ___O2 ___CO2 + ___H2O 2 C2H6 + 7 O2 4 CO2 + 6 H2O
Section 11.1 Assessment 1. Describe the steps in writing a balanced chemical equation. 2. Write the skeleton equation for the following reactions: Heating solid copper(II)sulfide in the presence of oxygen gas produces pure copper and sulfur dioxide gas. D a. CuS(s) + O2(g) Cu(s) + SO2(g) Iron metal and chlorine gas react to form solid iron(III)chloride. Fe(s) + Cl2(g) FeCl3(s) b.
Section 11.1 Assessment Solid aluminum carbonate decomposes to form solid aluminum oxide and carbon dioxide gas. c. Al2(CO3)3(s) Al2O3(s) + CO2(g) Solid magnesium reacts with aqueous silver(I)nitrate to form solid silver and aqueous magnesium nitrate. d. Mg(s) + AgNO3(aq) Ag(s) + Mg(NO3)2(aq)
Section 11.1 Assessment 3. Balance the following equations: ___SO2 + ___O2 ___SO3 2 2 a. 2 3 ___Fe2O3 + ___H2 ___Fe + ___H2O 3 b. ___P + ___O2 ___P4O10 4 5 c. 2 2 ___Al + ___N2 ___AlN d.
Section 11.2 Types of Chemical Reactions The five general types of reactions are synthesis, decomposition, single displacement, double displacement, and combustion.
Synthesis Reactions In a synthesis reaction, two or more substances react to form one product. Generic Reaction: A + B AB Actual Example: 2Mg + O2 2MgO
Predicting Products Predict the products for the following reactions: 1. Cu + S (Hint: copper is +1) 2Cu + S Cu2S 2. Be + O2 2Be + O2 2BeO 3. Fe + S (Hint: iron is +3) 2Fe + 3S Fe2S3
Decomposition Reactions A decomposition reaction occurs when a single reactant breaks down into two or more products. Generic Reaction: AB A + B Actual Example: 2HgO 2Hg + O2
Predicting Products Predict the products for the following reactions: 1. H2O 2H2O 2H2 + O2 2. HI 2HI H2 + I2 3. NH3 2NH3 N2 + 3H2
Single Displacement Reactions A single displacement reaction occurs when one element replaces a second element in a compound. Generic Reaction: A + BC B + AC Actual Example: Zn + Cu(NO3)2 Cu + Zn(NO3)2
Predicting Products Predict the products for the following reactions: 1. Br2 + NaI Br2 + 2NaI 2NaBr + I2 2. Fe + Pb(NO3)2 (Hint: iron is +3) 2Fe + 3Pb(NO3)2 2Fe(NO3)3 + 3Pb 3. Zn + H2SO4 Zn + H2SO4 ZnSO4 + H2 (Hint: zinc is +2)
Double Displacement Reactions A double displacement reaction involves the exchange of two positive ions between two compounds. Generic Reaction: AB + CD AD + CB Actual Example: 2NaCN + H2SO4 2HCN + Na2SO4
Predicting Products Predict the products for the following reactions: 1. CaBr2 + AgNO3 CaBr2 + 2AgNO3 2AgBr + Ca(NO3)2 2. FeS + HCl FeS + 2HCl FeCl2 + H2S 3. NaOH + Fe(NO3)3 3NaOH + Fe(NO3)3 Fe(OH)3 + 3NaNO3
Combustion Reactions A combustion reaction occurs when a substance burns in oxygen and produces a lot of heat and light. Generic Reaction: CxHy + O2 CO2 + H2O Actual Example: 2C8H18 + 25O2 16CO2 + 18H2O
Predicting Products Predict the products for the following reactions: 1. C6H6 + O2 2C6H6 + 15O2 12CO2 + 6H2O 2. C7H16 + O2 C7H16 + 11O2 7CO2 + 8H2O 3. C6H12O6 + O2 C6H12O6 + 6O2 6CO2 + 6H2O
Section 11.2 Assessment 1. What are the five types of chemical reactions? 2. Classify the following skeleton reactions: C3H6 + O2 CO2 + H2O b. Al(OH)3 Al2O3 + H2O c. Li + O2 Li2O d. Zn + AgNO3 Ag + Zn(NO3)2 a.
Section 11.2 Assessment 1. Complete and balance each equation: a. CaI2 + Hg(NO3)2 CaI2 + Hg(NO3)2 Ca(NO3)2 + HgI2 b. Al + Cl2 2Al + 3Cl2 2AlCl3 c. Ag + HCl (Hint: silver is +1) 2Ag + 2HCl H2 + 2AgCl d. C2H2 + O2 2C2H2 + 5O2 4CO2 + 2H2O e. MgCl2 MgCl2 Mg + Cl2
Section 11.3 Reactions in Aqueous Solution A complete ionic equation is an equation that shows dissolved ionic compounds as dissociated free ions. A spectator ion is an ion that is not directly involved in a reaction. Compounds that are aqueous will break into ions, and compounds that are solid will remain bonded.
Aqueous Ions When a compound is aqueous it breaks into its ions. Ex: Na+ and Cl- Mg+2 and 2Br- 2Al+3 and 3O-2 Li+ and NO3- 2K+ and CO3-2 Sr+2 and 2NO2- NaCl = MgBr2 = Al2O3 = LiNO3 = K2CO3 = Sr(NO2)2 =
Rules for Writing Complete Ionic Equations 1. Balance the equation. 2. Separate all aqueous substances into ions. 3. Leave any non-aqueous substances or precipitates together.
Complete Ionic Equations Regular Equation: AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) Complete Ionic Equation: Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) AgCl(s) + Na+(aq) + NO3-(aq)
Sample Problem Write the complete ionic equation for the following reaction: FeCl3(aq) + KOH(aq) Fe(OH)3(s) + KCl(aq) First balance the equation: FeCl3(aq) + 3KOH(aq) Fe(OH)3(s) + 3KCl(aq) Then write the complete ionic equation: Fe+3(aq) + 3Cl-(aq) + 3K+(aq) + 3OH-(aq) Fe(OH)3(s) + 3K+(aq) + 3Cl-(aq)
Practice Problems Write the complete ionic equation for the following reaction: NaOH(aq) + Fe(NO3)3(aq) Fe(OH)3(s) + NaNO3(aq) First balance the equation: 3NaOH(aq) + Fe(NO3)3(aq) Fe(OH)3(s) + 3NaNO3(aq) Then write the complete ionic equation: 3Na+(aq) + 3OH-(aq) + Fe+3(aq) + 3NO3-(aq) Fe(OH)3(s) + 3Na+(aq) + 3NO3-(aq)
Net Ionic Equations A net ionic equation shows only those particles involved in the reaction. The spectator ions have been removed. Ex: complete ionic equation 3Na+(aq) + 3OH-(aq) + Fe+3(aq) + 3NO3-(aq) Fe(OH)3(s) + 3Na+(aq) + 3NO3-(aq) X X X X When the spectator ions are removed, you are left with the net ionic equation: Fe+3(aq) + 3OH-(aq) Fe(OH)3(s)
Sample Problems To write a net ionic equation, you only consider non-aqueous substances and the ions that form them. Bi(NO3)3(aq) + H2S(aq) Bi2S3(s) + HNO3(aq) First, balance the equation: 2Bi(NO3)3(aq) + 3H2S(aq) Bi2S3(s) + 6HNO3(aq) Write only the ions involved in the reaction: 2Bi+3(aq) + 3S-2(aq) Bi2S3(s)
Practice Problems 1. Write the net ionic equation for the following reaction: Pb(NO3)2(aq) + H2SO4(aq) PbSO4(s) + HNO3(aq) First balance the equation: Pb(NO3)2(aq) + H2SO4(aq) PbSO4(s) + 2HNO3(aq) Write the net ionic equation: Pb+2(aq) + SO4-2(aq) PbSO4(s)
Practice Problems Write the net ionic equation for the following equation: Na3PO4(aq) + FeCl3(aq) NaCl(aq) + FePO4(s) First, balance the equation: Na3PO4(aq) + FeCl3(aq) 3NaCl(aq) + FePO4(s) Write the net ionic equation: PO4-3(aq) + Fe+3(aq) FePO4(s)
Predicting Precipitates You can predict whether a precipitate forms by using solubility rules. If a substance is soluble, then it will dissolve in water and be aqueous. If a substance is insoluble, then it will bond with another ion and will be a solid.
Solubility Rules alkali metals - Group 1 soluble NH4+ soluble NO3- soluble ClO3- soluble SO4-2 (except with Pb+2, Ag+, Hg2+2, Ba+2, Sr+2, and Ca+2) Cl- (exception Ag+, Pb+2, Hg2+2) CO3-2, PO4-3, CrO4-2, S-2, and OH- soluble soluble insoluble
Soluble or Insoluble? If any part of a compound is soluble, then the compound will be soluble. NH4Cl BaSO4 Na2SO4 Ca(OH)2 K3PO4 Mg(NO3)2 AgCl NiCrO4 Insoluble/Solid Soluble/Aqueous Insoluble/Solid Soluble/Aqueous Insoluble/Solid Soluble/Aqueous Soluble/Aqueous Insoluble/Solid
Predicting Precipitates Rules for Predicting Precipitates 1.Switch the ions and balance the charges to form the products. 2.Balance the equation. 3.Identify whether the products are solid or aqueous.
Sample Problem Predict the products for the following reaction: HCl(aq) + AgNO3(aq) First, form the products: HCl(aq) + AgNO3(aq) HNO3 + AgCl Then, balance the equation: HCl(aq) + AgNO3(aq) HNO3 + AgCl Finally, list states of matter: HCl(aq) + AgNO3(aq) HNO3(aq)+ AgCl(s)
Practice Problems 1. Predict the products for the following reaction: Pb(C2H3O2)2(aq) + LiCl(aq) First, form the products: Pb(C2H3O2)2(aq) + LiCl(aq) PbCl2 + LiC2H3O2 Then, balance the equation: Pb(C2H3O2)2(aq) + 2LiCl(aq) PbCl2 + 2LiC2H3O2 Finally, list states of matter: Pb(C2H3O2)2(aq) + 2LiCl(aq) PbCl2(s)+ 2LiC2H3O2(aq)
Practice Problems 2. Predict the products for the following reaction: NH4Cl(aq) + Ba(NO3)2(aq) First, form the products: NH4Cl(aq) + Ba(NO3)2(aq) NH4NO3 + BaCl2 Then, balance the equation: 2NH4Cl(aq) + Ba(NO3)2(aq) 2NH4NO3 + BaCl2 Finally, list the states of matter: 2NH4Cl(aq) + Ba(NO3)2(aq) 2NH4NO3(aq)+ BaCl2(aq)
Section 11.3 Assessment 1. What is a net ionic equation? 2. How can you predict the formation of a precipitate in a double displacement reaction? 3. Write the net ionic equation for the following reactions: a. Pb(C2H3O2)2(aq) + HCl(aq) PbCl2(s) + HC2H3O2(aq) Pb(C2H3O2)2(aq) + 2HCl(aq) PbCl2(s) + 2HC2H3O2(aq) Pb+2(aq) + 2Cl-(aq) PbCl2(s) b. (NH4)2S(aq) + Co(NO3)2(aq) CoS(s) + NH4NO3(aq) (NH4)2S(aq) + Co(NO3)2(aq) CoS(s) + 2NH4NO3(aq) Co+2(aq) + S-2(aq) CoS(s)
Section 11.3 Assessment 4. Predict the products for the following reactions: a. Na3PO4(aq) + CrCl3(aq) Na3PO4(aq) + CrCl3(aq) 3NaCl(aq) + CrPO4(s) b. Al2(SO4)3(aq) + NH4OH(aq) Al2(SO4)3(aq) + 6NH4OH(aq) 2Al(OH)3(s) + 3(NH4)2SO4(aq)
