Types of Chemical Reactions
Thermite reaction
Types of Reactions
•
There are five types of chemical
reactions we will talk about:
1.
2.
3.
4.
5.
•
Synthesis reactions
decomposition reactions
Single replacement reactions
Double replacement reactions
Combustion reactions
You need to be able to identify the type
of reaction and predict the product(s)
Steps to Writing Reactions
•
Some steps for doing reactions
1.
2.
3.
Identify the type of reaction
Predict the product(s) using the type
of reaction as a model
Balance it
Reminder!
1.
2.
Don’t forget about the diatomic
elements! For example, Oxygen is
O2 as an element.
In a compound, (MgO) it can’t be a
diatomic element because it’s not
an element anymore, it’s a
compound!
1. Synthesis reactions
•
Synthesis reactions occur
when two substances
(generally elements)
combine and form a
compound. (Sometimes
these are called combination
or addition reactions.)
SYNTHESIS
GENERAL FORMULA
reactant + reactant  1 product
• Basically: A + B  AB
•
•
Example: 2H2 + O2  2H2O
Example: C + O2  CO2
Synthesis Reactions
•
Here is another example of a synthesis
reaction
Practice
•
•
•
•
Predict the products. Write and balance
the following synthesis reaction equations.
Sodium metal reacts with chlorine gas
Na(s) + Cl2(g) 
Solid Magnesium reacts with fluorine gas
Mg(s) + F2(g) 
Aluminum metal reacts with fluorine gas
Al(s) + F2(g) 
2. Decomposition Reactions
•
Decomposition
reactions occur
when a compound
breaks up into the
elements or into a
few simpler
compounds
Decomposition
GENERAL FORMULA
•
•
•
•
1 Reactant  Product + Product
In general: AB  A + B
Example: 2 H2O  2H2 + O2
Example: 2 HgO  2Hg + O2
Decomposition Reactions
•
Another view of a decomposition reaction:
Decomposition Exceptions
•
Carbonates are a special case of a
decomposition reaction that does not go to
the elements.
•
Carbonates (CO32-) decompose to carbon
dioxide and a metal oxide
•
•
Example: CaCO3  CO2 + CaO
There are other special cases, but we will not
explore those in High School Chemistry
Practice
•
•
Predict the products. Then, write and
balance the following decomposition
reaction equations:
Solid Lead (IV) oxide decomposes
•
•
PbO2(s) 
Aluminum nitride decomposes
•
AlN(s) 
Practice
Identify the type of reaction for each of the
following synthesis or decomposition
reactions, and write the balanced equation:
N2(g) + O2(g)  (Nitrogen monoxide)
BaCO3(s) 
Co(s)+ S(s)  (Co+3)
NH3(g) + H2CO3(aq) 
NI3(s) 
Warm-Up

Sodium metal reacts with water to produce
aqueous sodium hydroxide and hydrogen
gas. Write the balanced equation for this
reaction.


2Na(g) + 2H2O(l)  2NaOH(aq) + H2(g)
Balance the equation
C6H14 + O2  CO2 + H2O
 2C6H14 + 19O2  12CO2 + 14H2O

3. Single Replacement Reactions
•
•
Single Replacement Reactions occur when
one element replaces another in a compound.
A metal can replace a metal (+) OR
a nonmetal can replace a nonmetal (-).
Single Replacement
General Formula
•
element + compound product + product
A + BC  AC + B (if A is a metal) CATIONIC OR
A + BC  BA + C (if A is a nonmetal) ANIONIC
(remember the cation always goes first!)
When H2O splits into ions, it splits into
H+ and OH- (not H+ and O-2 !!)
Single Replacement Reactions
•
Another view:
Trade-off lab

__Al(s) + __CuCl2(aq) → __AlCl3(aq) + __Cu(s)
What type of reaction was the trade-off lab?
 Single Replacement Reaction
 Is it cationic or anionic replacement?
 General form:
 A + BC → AC + B

Single Replacement Reactions
Write and balance the following single
replacement reaction equation:
• Zinc metal reacts with aqueous
hydrochloric acid
Zn(s) + 2 HCl(aq)  ZnCl2 + H2(g)
Note: Zinc replaces the hydrogen ion in the
reaction
Is it cationic or anionic?
Cationic
•
Single Replacement Reactions
•
Sodium chloride solid reacts with fluorine gas
2 NaCl(s) + F2(g)  2 NaF(s) + Cl2(g)
Note that fluorine replaces chlorine in the compound
•
•
Cationic or Anionic?
Anionic
4. Double Replacement Reactions
•
Double Replacement Reactions occur when
a metal replaces a metal in a compound and a
nonmetal replaces a nonmetal in a compound
Double Replacement
General Formula
•
•
compound + compound  product + product
AB + CD  AD + CB
Double Replacement Reactions
•
•
•
Think about it like “foil”ing in algebra, outside
ions go together & inside ions go together
Example:
AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)
Another example:
K2SO4(aq) + Ba(NO3)2(aq) 2 KNO3(aq) + BaSO4(s)
Group Quiz
Demo
 On a clean piece of paper, write both
group members names
 Speculate as to why specks of solid are
forming. One paragraph.
 Turn it into your folder

Practice
•
Predict the products. Balance the equation
1.
5.
HCl(aq) + AgNO3(aq) 
CaCl2(aq) + Na3PO4(aq) 
Pb(NO3)2(aq) + BaCl2(aq) 
FeCl3(aq) + NaOH(aq) 
H2SO4(aq) + NaOH(aq) 
6.
KOH(aq) + CuSO4(aq) 
2.
3.
4.
Warm Up

1.
2.
Predict the Products and write the net
ionic equation for the following reactions
KI (aq) + Pb(NO3)2(aq) →
A solution of calcium hydroxide is added
to a solution of potassium sulfate
Total Ionic Equations





Once you write the molecular equation (Double
replacement), you should check for reactants and
products that are soluble or insoluble.
We assume double replacement reactions are in water
We can use a solubility table to tell us what
compounds dissolve in water.
If the compound is soluble (dissolves in water), then it
splits the compound into its component ions
If the compound is insoluble (does NOT dissolve in
water), then it remains as a compound and the phase
label is (s).
Solubility Table
Solubility Trends

Gases only slightly dissolve in water


Water slightly dissolves in water (H+ and
OH-)


Treat as insoluble
Treat as insoluble
Strong acids and bases dissolve in water
Hydrochloric, Hydrobromic, Hydroiodic, Nitric,
Sulfuric, Perchloric Acids
 Group I hydroxides

Total Ionic Equations
Molecular Equation:
K2CrO4 + Pb(NO3)2 
PbCrO4 + 2 KNO3
Soluble
Insoluble
Soluble
Soluble
Total Ionic Equation:
2 K+ + CrO4 -2 + Pb+2 + 2 NO3- 
PbCrO4 (s) + 2 K+ + 2 NO3-
Net Ionic Equations
These are the same as total ionic
equations, but you should cancel out ions
that appear on BOTH sides of the
equation
Total Ionic Equation:
2 K+ + CrO4 -2 + Pb+2 + 2 NO3- 
PbCrO4 (s) + 2 K+ + 2 NO3Net Ionic Equation:
CrO4 -2 + Pb+2  PbCrO4 (s)

Net Ionic Equations

Try this one! Write the molecular, total ionic, and net
ionic equations for this reaction: Silver nitrate reacts
with Lead (II) Chloride in hot water.
Molecular:
Total Ionic:
Net Ionic:
5. Combustion Reactions
•
•
Combustion reactions
occur when an element
reacts with oxygen gas.
This is also called burning!!!
In order to burn something
you need the 3 things in the
“fire triangle”:
1) A Fuel
2) Oxygen to burn it with
3) Something to ignite the
reaction (spark)
Combustion Reactions
In general:
Hydrocarbon + O2  CO2 + H2O
Or
Element + O2  element oxide
• Products in combustion are ALWAYS carbon
dioxide and water or an oxide
•
4th Period brainteaser
Classify, Predict Products (if necessary), &
balance
1. BaCl2(aq) + H2SO4(aq) 
2. C6H12 + O2(g) 
3. Zn(s) + CuSO4(aq) 
4. K(s) + Br2(g)  KBr(s)
5. H2O2(aq)  O2(g) + H2O(l)
6. Na(s) + O2(g) 
Combustion
Reactions
Edgar Allen Poe’s
drooping eyes and
mouth are potential
signs of CO poisoning.
CO is a by-product of
the combustion
process if the
hydrocarbon does not
fully combust.
Combustion
•
Example
•
•
C5H12 + 8O2  5CO2 + 6H2O
Write the products and balance the
following combustion reaction:
•
C4H10 + O2 
Activity Series of Metals
Matter tends to react in
such a way that more
reactive substances form
less reactive substances.
Some metals are higher in
reactivity than others
 Activity series: a list of
metals arranged in
decreasing reactivity (used
for metal and hydrogen
single replacement
reactions)

42
5th period Warm-up
Classify, Predict Products (if necessary), &
balance
1. BaCl2(aq) + H2SO4(aq) 
2. C6H12 + O2(g) 
3. Zn(s) + CuSO4(aq) 
4. K(s) + Br2(g)  KBr(s)
5. H2O2(aq)  O2(g) + H2O(l)
6. Na(s) + O2(g) 
I will go over the warm-up later in the period.
On a blank piece of paper…
Write one thing you know about chemical
equations.
 Write one thing you need to know but
struggle with about chemical equations

Activity Series
The higher the metal on the activity series,
the more active that metal.
 Translation: higher metals on the chart will
form ions in solution (dissolve in water…ie.
Aqueous) the other metal in the reaction
will precipitate (solid)
 Use the activity series on the back of
periodic table to predict products and
assign phase labels

Predict whether a reaction occurs
If a reaction occurs, predict the
products. (don’t forget phase labels)
Na (s) + H2O (l)→
 Fe (s) + HCl (aq) →
 Fe (s) + Cr(NO3)3(aq) →
 Ni (s) + Pb(NO3)2(aq) →
 Ag (s) + Mg(NO3)2(aq) →
 Zn (s) + Co(NO3)2(aq) →

Summary of Reactions

For the test

You should be able to ….
 Classify
reactions
 Predict Products
 Write balanced molecular equations
 Write balanced net ionic equations
Synthesis and Decomposition
General forms:
 Synthesis A + B → AB
 Decomposition AB → A + B
 If you can’t see the general form of a
reaction try labeling the reactants and
products with “A” and “B”.
 Know how to classify these reactions

Combustion

Memorize the two general forms
Hydrocarbon + O2(g)  CO2(g) + H2O(l)
Element + O2(g)  element oxide


Balancing the first general form can be tricky…..
Just keep working at it.
You must be able to classify and predict
products in these reactions.
Single Replacement
Use the Activity series on the back of your
periodic table to determine whether a reaction
occurs.
 If a reaction occurs, predict products and
balance….don’t forget phase labels.
 Classify as cationic or anionic
 General form:
 A + BC → AC + B (cationic)
Or
 A + BC → BA + C (anionic)

Double Replacement
Predict products
 Use your Solubility Rules (pg 178) to
determine whether a reaction occurs.
 If a reaction occurs, determine phases of
products
 Determine the Net ionic equation if asked
to do so.
 General Form:
 AB + CD → AD + CB

From Warm-up
1.
2.
3.
4.
5.
6.
BaCl2(aq) + H2SO4(aq) 
C6H12 + O2(g) 
Zn(s) + CuSO4(aq) 
K(s) + Br2(g)  KBr(s)
H2O2(aq)  O2(g) + H2O(l)
Na(s) + O2(g) 
Demo Gas Collection
In your pairs, the person with the longest
eyelashes go get your lab books on the back
table.
 Technique for collecting gas via water
displacement
 First reaction

Zinc metal is placed in a jar. Hydrochloric acid is
added to the jar
 Write the chemical equation for this reaction and
classify it.

Demo Gas Collection
Technique for collecting gas via water
displacement
 Second reaction

Hydrogen Peroxide is poured into a jar. A
catalyst (NaI) is then put into the jar.
Hydrogen peroxide then breaks down into
oxygen gas and liquid water.
 Write the chemical equation for this reaction
and classify it.

On a blank piece of paper…
(5 minutes)
What gas was formed in reaction #1?
 What happened when the burning splint
was placed into the test tube?
 What gas was formed in reaction #2?
 What happened when the glowing splint
was placed into the test tube?
 What did you learn from reaction #1?
 What did you learn from reaction #2?

Demo







Reaction #3
Solid calcium carbonate reacts with hydrochloric
acid (HCl)
Write an equation with your reactants
Write an If….and…then… statement to test for
which gas is produced.
Demo
What actually happened?
What can you conclude about the gas being
produced?
Follow-up
Write one thing you learned about
chemical equations today.
 Write one thing you still need to know
about chemical equations

In pairs…
The person with the brightest shirt go get a
white board and dry erase marker.
 Taking turns answer the following
questions.
 Hold the white board up to show me your
answer.

Question 1
Classify the following reactions
 2NaBr + Ca(OH)2  CaBr2 + 2NaOH
 N2 + 3H2  2NH3
 2KClO3  2KCl + 3O2
 2NaCl + F2  2NaF + Cl2
 CH4 + 2O2  CO2 + 2H2O
 4P + 10O2  2P2O5

Question 2
If a reaction occurs, predict the products
and balance
 FeCl3 + NaOH 
 Zn + LiOH 
 K + MgBr 

Question 3
Write the net ionic equations
 NaBr + CaF2 
 FeCl3 + NaOH 
 Ca(NO3)2 + Na2SO4 

Question 4
Balance
a. __ HgO → __ Hg + __O2
b. __ Fe + __ O2 → __ Fe2O3
c. __ KClO3 → __ KCl + __ O2
d. __ Ca(OH)2 + __ H2SO4 → __H2O + __ CaSO4
e. __ Cu + __ AgNO3 → __ Cu(NO3)2 + __ Ag
f. __ C2H6 + __O2 → __ CO2 + __H2O

Warm-up

Balance and Classify the following equation:


Mg (s) + CO2 (g) + O2 (g) → MgCO3 (s)
For Carbon dioxide, write the following items:
Chemical formula
 Lewis dot structure
 VSEPR shape
 Polarity of bonds
 Overall polarity of the molecule

Warm-Up
1. Write a balanced chemical equation for the
following reactions
Cu(NH3)4SO4 → solid Copper(II) sulfate + ammonia gas
Aluminum + Fluorine gas → Aluminum fluoride
2. Classify these reactions
Warm-up
Predict products and classify these reactions
Na2CO3(s) 
NH3(g) + H2SO3(aq) 
NF3(s) 
H2 (g) + O2 (g) 
Quiz
Classify the reactions
 Predict the products (when necessary)
and write a balanced chemical equation
 Write the net ionic equation when
appropriate
 Don’t forget phase labels
