Chemical
Equations Part 1
A Directed Learning Activity
for Hartnell College
Chemistry 1
Funded by the Title V – STEM Grant
#P031S090007 through Hartnell College
For information contact lyee@hartnell.edu
Start
Student Learning Objectives
This tutorial will help you to:
1. Predict products of single and doublereplacement reactions
2. Generate formula, total ionic and net
ionic equations using solubility and acid
strength information
Next
Getting Started



This set of Power Point slides will lead you through a
series of short lessons and quizzes on the topics
covered by this Directed Learning Activity tutorial.
Move through the slideshow at your own pace.
There are several hyperlinks you can click on to
take you to additional information, take quizzes,
get answers to quizzes, and to skip to other lessons.
You can end this slide show at any time by hitting
the “ESC” key on your computer keyboard.
Next
Table of Topics
 What
You Should Know
 Classes of Chemical Reactions
 Single-replacement Reactions
 Double-replacement Reactions
Next Slide
What You Should Know
 Write
correct chemical formulas for
elements, ions and compounds
 Balance chemical formula equations
 Know the difference between strong and
weak acids and bases in solution
Next Slide
Classes of Chemical
Reactions
A Quick Overview of Synthesis, Decomposition,
Single and Double-replacement Reactions
Next Slide
The Four Major Classes of
Chemical Reactions
There are many different types of chemical
reactions, but they can be broken down
into these major categories:
 Synthesis (Combination) Reactions
 Decomposition Reactions
 Single-Replacement Reactions
 Double-Replacement Reactions
The next few slides will explain the general
characteristics of each category
Next Slide
Synthesis
(Combination)Reactions
Synthesis reactions can be written in symbols as:
𝐴+𝐵 →𝐶
Where A and B can be either elements or
compounds and C is a new compound.
There are three kinds of synthesis reactions:
1.
2.
3.
Elements combine to form a compound
An element and a compound combine
Two compounds combine
Next Slide
Decomposition Reactions
Decomposition reactions can be written in
symbols as
𝐴𝐴 → 𝐴 + 𝐵
Where AB is a compound, while A and B are
elements or simpler compounds.
There are three kinds of decomposition
reactions:
1.
2.
3.
Two (or more) elements are formed
Elements and compounds form
Two (or more) compounds form
Next Slide
Single-replacement Reactions
Single-replacement reactions can be
symbolized as
𝐴 + 𝐵𝐵 → 𝐴𝐴 + 𝐵
Where A and B are two elements and BC and
AC are two compounds.
There are three basic kinds of singlereplacement reactions:
1.
2.
3.
A metal replaces another metal
A metal replaces H to form H2 (g)
A nonmetal replaces another nonmetal
Next Slide
Double-replacement
Reactions
Double-replacement reactions, also called
“exchange” reactions, may be symbolized:
𝐴𝐴 + 𝐶𝐶 → 𝐴𝐴 + 𝐵𝐵
Where AB and CD are the original compounds and
AD and BC are new compounds formed when the
original compounds exchange ions or atoms.
There are three kinds of double-replacement
reactions:
1.
2.
3.
Reactions in solution that form a precipitate (an
insoluble solid)
Reactions that form a gas
Reactions that form water (neutralization
reactions)
Next Slide
Details of Singlereplacement Reactions
𝐴 + 𝐵𝐵 → 𝐴𝐴 + 𝐵
Next Slide
Example: A Metal Replaces Another
Metal in a Compound
𝐶𝐶 𝑠 + 2 𝐴𝐴𝐴𝐴3 𝑎𝑎
→ 𝐶𝐶 𝑁𝑁3 2 𝑎𝑎 + 2 𝐴𝐴 (𝑠)
In this case, solid Cu metal reaction with an
aqueous solution of AgNO3. The Cu and Ag
are exchanged and Cu(NO3)2 is formed in
solution while solid Ag metal is formed.
Next Slide
Example: A Metal Replaces H to
Form H2 (g)
𝑀𝑀 𝑠 + 2 𝐻𝐻𝐻 𝑎𝑎 → 𝑀𝑀𝑀𝑀2 𝑎𝑎 + 𝐻2 (𝑔)
In this example, solid Mg metal reacts with HCl
in solution. MgCl2 is the product formed in
solution, while H2 gas is released. Note: in
balancing this type of equation, remember that
hydrogen is one of the diatomic molecular
elements. Also, the most reactive metals
(Group 1A and 2A) can undergo this type of
reaction with water to form hydrogen gas. It is
important to remember that this type of
reaction often requires a strong acid,
depending on the reactivity of the metal.
Next Slide
Example: A Nonmetal
Replaces Another Nonmetal
𝐶𝐶2 𝑎𝑎 + 2 𝑁𝑁𝑁 𝑎𝑎 → 2 𝑁𝑁𝑁𝑁 𝑎𝑎 + 𝐼2 𝑎𝑎
In this case a halogen (Group 7A) replaces
another halogen in a compound. Note: as
with hydrogen, halogens are diatomic
molecular elements.
Next Slide
Quiz Questions
𝑍𝑍 𝑠 + 𝐶𝐶𝐶𝐶4 𝑎𝑎 → ? + ?
𝐶𝐶 𝑠 + 𝐻2𝑆𝑆4 𝑎𝑎 → ? + ?
𝐶𝐶2 𝑎𝑎 + 𝐶𝐶𝐶𝐶2 𝑎𝑎 → ? + ?
Answers to Quiz Questions
Answers to Quiz Questions
𝑍𝑍 𝑠 + 𝐶𝐶𝐶𝐶4 𝑎𝑎 → 𝑍𝑍𝑍𝑍4 𝑎𝑎 + 𝐶𝐶 (𝑠)
𝐶𝐶 𝑠 + 𝐻2𝑆𝑆4 𝑎𝑎 → 𝐶𝐶𝐶𝐶4 𝑎𝑎 + 𝐻2(𝑔)
𝐶𝐶2 𝑎𝑎 + 𝐶𝐶𝐶𝐶2 𝑎𝑎 → 𝐶𝐶𝐶𝐶2 𝑎𝑎 + 𝐵𝐵2(𝑎𝑎)
Review this lesson
Next lesson
Double-replacement
Reactions
𝐴𝐴 + 𝐶𝐶 → 𝐴𝐴 + 𝐵𝐵
Next slide
Example: Reactions in Solution
that Form a Precipitate
𝐴𝐴𝐴𝐴3 𝑎𝑎 + 𝑁𝑁𝑁𝑁 𝑎𝑎
→ 𝑁𝑁𝑁𝑁3 𝑎𝑎 + 𝐴𝐴𝐴𝐴 (𝑠)
A precipitate is a solid that forms in solution.
In this example, the two reactants are both
soluble in water. One of the products,
NaNO3, is also soluble in water. The other
product, AgCL, forms a solid precipitate.
Note: there are cases when both products
will form a precipitate.
Next Slide
Example: Reactions that Form a
Gas
𝑁𝑁𝑁𝑁𝑁3 𝑎𝑎 + 𝐻𝐻𝐻 (𝑎𝑎) → 𝑁𝑁𝑁𝑁 𝑎𝑎 + 𝐻2𝐶𝐶3 (𝑎𝑎)
→ 𝑁𝑁𝑁𝑁 𝑎𝑎 + 𝐻2𝑂 𝑙 + 𝐶𝐶2 (𝑔)
In this reaction, two aqueous species eventually
produce another aqueous species and a gas.
Note: H2CO3, one of the products of the initial
reaction, rapidly decomposes to create the gas
CO2. Typical gases that can be produced in
this kind of reaction include H2S. Note that this
type of reaction may require a strong acid.
Next Slide
Example: Reactions that Form
Water
𝐻𝐻𝐻3 𝑎𝑎 + 𝑁𝑁𝑁𝑁 𝑎𝑎 → 𝑁𝑁𝑁𝑁3 𝑎𝑎 + 𝐻2𝑂(𝑙)
When an acid and a base are the reactants,
this type of reaction is referred to as a
neutralization reaction. The aqueous product is
referred to as a “salt”. The salt has the cation
from the base and the anion from the acid.
Metal oxides can also react with acids to form
water as a product.
Next Slide
Quiz Questions
𝐶𝐶 𝑁𝑁3
2
𝑎𝑎 + 𝑁𝑁2𝐶𝐶3 𝑎𝑎 → ? + ?
𝑁𝑁2𝑆 𝑎𝑎 + 2 𝐻𝐻𝐻 𝑎𝑎 → ? + ?
𝐵𝐵𝐵 𝑠 + 2 𝐻𝐻𝐻3 𝑎𝑎 → ? + ?
Check answers
Answers to Quiz Questions
𝐶𝐶 𝑁𝑁3 2 𝑎𝑎 + 𝑁𝑁2𝐶𝐶3 𝑎𝑎
→ 2 𝑁𝑁𝑁𝑁3 𝑎𝑎 + 𝐶𝐶𝐶𝐶3 (𝑠)
𝑁𝑁2𝑆 𝑎𝑎 + 2 𝐻𝐻𝐻 𝑎𝑎 → 2 𝑁𝑁𝑁𝑁 𝑎𝑎 + 𝐻2𝑆(𝑔)
𝐵𝐵𝐵 𝑠 + 2 𝐻𝐻𝐻3 𝑎𝑎
→ 𝐵𝐵 𝑁𝑁3 2 𝑎𝑎 + 𝐻2𝑂 (𝑙)
Review lesson
Next lesson
Net Ionic Equations
Getting Rid of the Spectators
Next slide
Representing Reactions
When a reaction occurs in aqueous solution, we
can write the formula equation, which uses the
neutral formulas or symbols for the reactants
and products. These are the kinds of equations
you have already practiced writing. In certain
instances, there are other ways of representing
the reaction.
The total ionic equation (TIE) separates all the
neutral compounds into the ionic species they
form in solution.
The net ionic equation removes those ions from
the equation that do not result in creating a
new product. Those ions are called “spectator
ions”, since they don’t actually participate in
the formation of a new product.
Next slide
Example: Precipitation
Let’s use a reaction you have already seen.
𝐶𝐶 𝑁𝑁3 2 𝑎𝑎 + 𝑁𝑁2𝐶𝐶3 𝑎𝑎
→ 2 𝑁𝑁𝑁𝑁3 𝑎𝑎 + 𝐶𝐶𝐶𝐶3 (𝑠)
This would be the formula equation.
Next slide
If we now break down everything that is soluble
into ions and rewrite the equation, we obtain
the total ionic equation:
Ca2+ (aq) + 2 NO3- (aq) + 2 Na+ (aq) + CO3 2- (aq) →
CaCO3 (s) + 2 Na+ (aq) + 2 NO3- (aq)
Inspecting this equation, we see that there are
several ions that appear on both sides of the
equation. These are the spectator ions. If we
remove these, we obtain the net ionic
equation:
Ca2+ (aq) + 2 NO3- (aq) + 2 Na+ (aq) + CO3 2- (aq) →
CaCO3 (s) + 2 Na+ (aq) + 2 NO3- (aq) or
Ca2+ (aq) + CO3 2- (aq) → CaCO3 (s)
Next slide
We can do similar procedures to the formula
equations for the reactions that form gases and
for neutralization of acids and bases.
What if you are only given the starting materials
and have to predict the products of the
formula equation before you generate the net
ionic equation?
Then, you will have a use a table of solubilities
like to the one on the next slide. There is
probably one similar to it in your lecture text.
You also need to know if the acids and bases
are weak or strong. Remember that weak acids
and bases do not completely dissociate and
will be molecular species in solution. There is
also an example table of strong acid and base
on another slide.
Solubility Table
Anions
Cations
C2H3O2-
AsO4-
Br -
CO32-
Cl -
CrO42-
OH -
I-
NO3-
C2O42-
O 2-
PO43-
SO42-
S 2-
SO32-
Al 3+
aq
I
aq
-
aq
-
I
aq
aq
-
I
I
aq
d
-
NH4+
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
-
aq
aq
aq
aq
Ba 2+
aq
I
aq
I
aq
I
sl. aq
aq
aq
I
sl. aq
I
I
d
I
Bi 3+
-
sl. aq
d
I
d
-
I
I
aq
I
I
sl. aq
d
I
-
Ca 2+
aq
I
aq
I
aq
aq
I
aq
aq
I
I
I
I
d
I
Co 2+
aq
I
aq
I
aq
I
I
aq
aq
I
I
I
aq
I
I
Cu 2+
aq
I
aq
I
aq
I
I
-
aq
I
I
I
aq
I
-
Fe 2+
aq
I
aq
sl. aq
aq
-
I
aq
aq
I
I
I
aq
I
sl. aq
Fe 3+
I
I
aq
I
aq
I
I
-
aq
aq
I
I
aq
I
-
Pb 2+
aq
I
I
I
I
I
I
I
aq
I
I
I
I
I
I
Mg 2+
aq
d
aq
I
aq
aq
I
aq
aq
I
I
I
aq
d
sl. aq
Hg2 2+
sl. aq
I
I
I
I
sl. aq
-
I
aq
I
I
I
I
I
-
Hg 2+
aq
I
I
I
aq
sl. aq
I
I
aq
I
I
I
d
I
-
Ni 2+
aq
I
aq
I
aq
I
I
aq
aq
I
I
I
aq
I
I
K+
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
Ag +
sl. aq
I
I
I
I
I
-
I
aq
I
I
I
I
I
I
Na +
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
aq
Sr 2+
aq
-
aq
I
aq
I
aq
aq
aq
-
-
I
I
I
-
Zn 2+
aq
I
aq
I
aq
I
I
aq
aq
I
I
I
aq
I
I
N
e
x
t
Examples of Strong Acids &
Bases
 Strong

HClO4, H2SO4, HI, HBr, HCl, HNO3
 Strong

acids in aqueous solutions:
bases in aqueous solutions:
LiOH, KOH, NaOH, Ca(OH)2
Remember that “strong” refers to species
that dissociate (almost) completely to
ions in water.
Next slide
Quiz Questions
Write the net ionic equations for these
reactions:
K2SO4 (aq) + BaBr2 (aq) → ? + ?
Na2CO3 (aq) + 2 HCl (aq) → ? + ? + ?
Ca(OH)2 (aq) + 2 HCl (aq) → ? + H2O (l)
Next slide
Answers to Questions
K2SO4 (aq) + BaBr2 (aq) → 2 KBr (aq) + BaSO4 (s)
Ba2+ (aq) + SO42- (aq) → BaSO4 (s)
Comment: look at solubility of the possible products to
see that one of the products is solid. Delete the
spectator ions to yield the net ionic equation.
Na2CO3 (aq) + 2 HCl (aq) →
2 NaCl (aq) + H2O (l) + CO2 (g)
2 H+ (aq) + CO32- (aq) → H2O (l) + CO2 (g)
Comment: Refer to gas generation example. Delete
the spectator ions to generate the net ionic equation.
Next slide
Ca(OH)2 (aq) + 2 HCl (aq) →
CaCl2 (aq) + 2 H2O (l)
2 H+ (aq) + 2 OH- (aq) → 2 H2O (l)
Comment: This net ionic equation is common to all
acid-base neutralization reactions
Review lesson
Next slide
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Directed Learning Activity tutorial. We
hope that this has helped you to better
understand this topic.
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This document has been prepared in
compliance with US & International
Copyright Laws
© 2011 Hartnell College
Funded by the Title V – STEM Grant
#P031S090007 through Hartnell College
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