Transcript Chapter #7

Chapter #6
Chemical Reactions
Chapter 6
Chemical Reactions
• A chemical reactions is an abbreviated way to show a
chemical change
• A chemical change alters the physical and chemical
properties of a substance
• Factors that indicate a chemical change
–
–
–
–
Change in color
Temperature change
Change in odor
Change in taste (we do not taste chemicals)
• Reactions always contain an arrow that separates the
reactants from the products
Reactants
Products
Chapter 6
Chemical Change Evidence
Chapter 6
Chemical Change Evidence
What is a clue that a chemical reaction has
occurred?
a)
b)
c)
d)
The color changes.
A solid forms.
Bubbles are present.
A flame is produced.
Chapter 6
Chemical Change Evidence
What is a clue that a chemical reaction has
occurred?
“Colorless hydrochloric acid is added to a
red solution of cobalt(II) nitrate, turning the
solution blue.”
a)
b)
c)
d)
The color changes.
A solid forms.
Bubbles are present.
A flame is produced.
Chapter 6
Chemical Change Evidence
What is a clue that a chemical reaction has
occurred?
“A solid forms when a solution of sodium
dichromate is added to a solution of lead
nitrate.”
a)
b)
c)
d)
A gas forms.
A solid forms.
Bubbles are present.
A flame is produced.
Chapter 6
Types of Chemical Reactions
•
Combination reaction (synthesis)
– Elements for reactants
– Examples:
H2 + O2
N2 + H2
Al + O2
H2O
NH3
Al2O3
The Law of Conservation of matter, states
matter cannot be created nor destroyed, the
means equations must be balanced.
Chapter 6
Types of Chemical Reactions
Balance the first equation
H2 + O2
H2O
Note two oxygen atoms on the reactant side and only
one on the product side, therefore place a two in front
of water
Chapter 6
Types of Chemical Reactions
Balance the first equation
H2 + O2
2H2O
Note two oxygen atoms on the reactant side and
only one on the product side, therefore place
a two in front of water
The two now doubles everything in water, thus 4
hydrogen and 2 oxygen. Now place a 2 in
front of hydrogen.
Chapter 6
Types of Chemical Reactions
Balance the first equation
2H2 + O2 2H2O
Note two oxygen atoms on the reactant side and only
one on the product side, therefore place a two in front
of water
The two now doubles everything in water, thus 4
hydrogen and 2 oxygen. Now place a 2 in front of
hydrogen.
Chapter 6
Types of Chemical Reactions
Now balance the second equation
N2 + H2
NH3
Note two nitrogen atoms on the reactant side and only
one on the product side.
Place a 2 in front of ammonia
Chapter 6
Types of Chemical Reactions
Now balance the second equation
N2 + H2
2NH3
Note two nitrogen atoms on the reactant side
and only one on the product side.
Place a 2 in front of ammonia. This makes 2
nitrogen atoms and 6 hydrogen atoms. Now
place a 3 in front of hydrogen to balance
hydrogen atoms.
Chapter 6
Types of Chemical Reactions
Now balance the second equation
N2 + 3 H2
2NH3
Note two nitrogen atoms on the reactant side and only
one on the product side.
Place a 2 in front of ammonia. This makes 2 nitrogen
atoms and 6 hydrogen atoms. Now place a 3 in front of
hydrogen to balance hydrogen atoms.
Chapter 6
Types of Chemical Reactions
• Decomposition Reaction
– Compounds form simpler compounds or
elements.
– Examples
H2O
H2 + O2
Chapter 6
Types of Chemical Reactions
• Decomposition Reaction
– Compounds form simpler compounds or
elements.
– Examples
2H2O
H2 + O2
Chapter 6
Types of Chemical Reactions
• Decomposition Reaction
– Compounds form simpler compounds or
elements.
– Examples
2H2O
2 H2 + O2
• Notice decomposition reactions are the
opposite of combination reactions
Chapter 6
Types of Chemical Reactions
• Single Replacement Reactions
Single Replacement reactions have an element and a
compound for reactants.
Example:
Zn + HCl
How do we predict the products? Trade places with
the metal or nonmetal with the metal or nonmetal in
the compound
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element and a
compound for reactants.
Example:
Zn + HCl
How do we predict the products? Trade places with
the metal or nonmetal with the metal or nonmetal in
the compound
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Example:
Zn + HCl
ZnCl + H
Now make the products stable. Slide with Clyde
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Example:
Zn + HCl
ZnCl2 + H2
Now make the products stable. Slide with Clyde
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Example:
Zn + HCl
ZnCl2 + H2
Now make the products stable. Slide with Clyde
Now Balance
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Example:
Zn + 2HCl
ZnCl2 + H2
Now make the products stable. Slide with Clyde
Now Balance
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Another Example:
Cl2 + MgBr2
How do we predict the products? Trade places
with the metal or nonmetal with the metal or
nonmetal in the compound. In this case we
are trading nonmetals
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Another Example:
Cl2 + MgBr2
Br + MgCl
How do we predict the products? Trade places
with the metal or nonmetal with the metal or
nonmetal in the compound. In this case we
are trading nonmetals
Chapter 6
Types of Chemical Reactions
Single Replacement reactions have an element
and a compound for reactants.
Another Example:
Cl2 + MgBr2
Br2 + MgCl2
How do we predict the products? Trade places
with the metal or nonmetal with the metal or
nonmetal in the compound. In this case we
are trading nonmetals
Chapter 6
Types of Chemical Reactions
• Double Replacement Reactions
Double Replacement reactions contain
compounds as reactants.
HCl + Ca(OH)2
CaCl + HOH
Check formulas, and slide with Clyde when
necessary
Chapter 6
Types of Chemical Reactions
Double Replacement reactions contain
compounds as reactants.
HCl + Ca(OH)2
CaCl 2 + HOH
Check formulas, and slide with Clyde when
necessary
Chapter 6
Types of Chemical Reactions
Double Replacement reactions contain
compounds as reactants.
2HCl + Ca(OH)2
CaCl 2 + 2HOH
Check formulas, and slide with Clyde when
necessary
Now Balance!
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
H2 + O2
CH4 + O2
What is the oxide of hydrogen?
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
H2 + O2
CH4 + O2
What is the oxide of hydrogen? Water
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
H2 + O2
H2O
CH4 + O2
What is the oxide of hydrogen? Water
And the oxide of carbon?
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
H2 + O2
H2O
CH4 + O2
CO2 + H2O
What is the oxide of hydrogen? Water
And the oxide of carbon? Carbon dioxide
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
2H2 + O2
2H2O
CH4 + O2
CO2 + H2O
Now balance
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
2H2 + O2
2H2O
CH4 + O2
CO2 + 2H2O
Now balance
Chapter 6
Types of Chemical Reactions
Combustion Reactions occur when an element or
compound combine with oxygen to produce oxides
of each element.
2H2 + O2
2H2O
CH4 + 2O2
CO2 + 2H2O
Now balance
Chapter 6
The End