4.2 – 5.4: Types of Chemical Reactions
Chemical Reactions
• There millions of known chemical reactions!
• We can group these reactions by their reaction patterns, making it easier to predict products of
reactions.
• When predicting products for any reaction, follow these steps:
Step 1:
Step 2:
Step 3:
Step 4:
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To predict states:
• An ELEMENT on its own – use the _____________________________
• A COMPOUND:
• IONIC will always be _____________
• MOLECULAR are usually _________
• Exception: H2O is __________
• ACIDS are ______________
• Any SOLUTION is _______________
•
Other important rules to remember:
• Whenever a NEW ionic compound is formed, use the ionic charges to determine the formula!
• HOFBrINCl formulas
• ie: the element chlorine is not _____, it is always _______!
1. Synthesis Reactions
Definition:
Pattern:
a) Synthesis of Ionic Compounds (Metal and Non-Metal)
• Use _______________________ of the reactants to predict the products
Example: The reaction of magnesium with oxygen
b) Synthesis of Molecular Compounds (Non-Metals)
i) Reactions involving Hydrogen
• Although hydrogen is in Group 1, it is a ____________ and usually forms _______________
compounds.
• But, we still use ___________________ to predict the products.
Example: Synthesis of hydrogen chloride
ii) Reactions not involving Hydrogen
• Difficult to predict the products. They often depend on the reaction conditions.
• Only way to identify the products is by chemical tests.
• For our purposes, simply ______________________________________________________
Example: the synthesis of sulfur trioxide
c) Synthesis Reactions involving oxides
i) Acidic oxides
• ____________react with _____________ to form ___________________________________
Example: The synthesis of carbon dioxide
•
Then, when dissolved in __________, non-metallic oxides produce ____________ solutions
(the oxyacid that corresponds to the original non-metal is formed)
Example: Carbon dioxide reacts with water
ii) Basic oxides
• ___________ react with ______________ to form __________________________________
Example: Sodium and oxygen
•
Then, when dissolved in ______________, metallic oxides produce _____________ solutions
(The metal combines with hydroxide)
Example: Sodium oxide reacts with water
Practice!
a) Show the synthesis of calcium oxide. Then, show the reaction when it reacts with water.
b) Show the 2 step synthesis of sulfuric acid.
2. Decomposition Reactions
Definition:
Pattern:
a) Simple Ionic or Molecular Compounds
• The compound breaks down into its ________________
Example: Decomposition of potassium chloride
Example: Decomposition of ammonia
b) Complex Compounds
• A compound breaks down into two ____________________
• Often difficult to predict, except:
• Carbonates decompose into a ___________________ and ________________
Example: The decomposition of calcium carbonate
Example: The decomposition of lithium carbonate
3. Single Displacement Reactions
Definition:
Pattern:
Example: Zinc reacts with copper (II) sulfate
Example: Bromine reacts with magnesium oxide
The Activity Series of Metals
• Not all single displacement reactions “on paper” actually occur. It depends on the
________________ of the two metals.
•
The Activity Series is a list of metals and their reactivity. (see handout)
•
The most reactive metals are on ______________
•
An element (on its own) can only displace another element (in a compound) if it is
__________________________ (________________ on the activity series)
•
•
Otherwise, ______________________________ occurs
The farther apart two elements are, the _______________ the reaction
a) Reactions Involving a Metal and an Ionic Compound
•
Use the activity series to determine if a reaction occurs
•
If reaction occurs, write the products
•
If no reaction occurs, just write NO REACTION.
Example: Magnesium metal is placed in a solution of copper (II) sulfate
Example: Lead is placed in a zinc nitrate solution
b) Reactions Involving a Metal and Water or Acid (H+)
•
Same idea as above: Hydrogen is also on the activity series
**Treat acids and water as if they are ionic compounds (with an H+)
Example: Lithium is added to sulfuric acid
Example: Sodium is added to water
c) Reactions Involving a Non-Metal
•
Halogens have their own activity series – follows group pattern
Example: The reaction of chlorine and potassium iodide
4. Double Displacement Reactions
Definition:
Pattern:
** Like replaces like (metals switch places)
Recall: Solubility
•
Solution -
•
Solute –
•
Solvent –
•
Solubility –
•
(aq) –
•
(s) –
a) Precipitation Reactions (Two ionic compounds)
•
Reactions between two compounds don’t ALWAYS happen. It depends on their solubility.
•
If a precipitate forms, a reaction occurs, because one of the new compounds is
____________________ in the solution of the other compound.
•
If no precipitate forms, there is ________________
•
How do we determine if a precipitate forms? USE the ______________________ (see handout)
•
Practice: Determine if the following compounds are soluble (aq) or insoluble (s) in water:
a) AgCl
b) MgCl2
c) Na2CO3
d) BaSO4
Example: Solutions of potassium chloride and silver nitrate are combined.
Example: Solutions of potassium sulfate and iron (III) chloride are combined.
b) Reactions that Produce a Gas
•
Double displacement reactions involving an ________ can produce ________________. Gases
may be produced in two ways:
1. Directly
Example: a metal sulfide will produce hydrogen sulfide gas
Gases formed:
Sulfides  H2S
Carbonates  CO2
Sulfites  SO2
2. Indirectly - an unstable product can decompose into __________ and _________
Example: A carbonate
Example: A sulfite
c) Neutralization Reactions
i) With a hydroxide compound
Pattern:
Acid has _______, base has _______ - these ions combine to form ______________________
Other cation and ion combine to form a ___________ (ionic compound)
Example: Hydrochloric acid and sodium hydroxide
ii) With a carbonate compound
Pattern:
Example:
Calcium carbonate reacts with sulfuric acid to produce carbonic acid:
But, carbonic acid immediately decomposes into water and carbon dioxide
The chemical equation for the net reaction of calcium carbonate and sulfuric acid is:
5. Combustion Reactions
Definition:
•
A chemical reaction in which____________ burns in _____________
•
Common fuels are ________________________ with the general formula _____________ Methane
is ___________, propane is ______________
•
Releases energy in the form of __________ and ___________
a) Complete Combustion
Formula:
•
Occurs when there is ________________________________
•
Products are ______________________________________________________________
•
The ________ way to burn a fuel – it produces the ____________________________________
•
The __________________on a gas stove is an example of complete combustion
Example: Burning of natural gas, CH4
b) Incomplete Combustion
Formula:
•
Occurs when the oxygen supply is _______________
•
Products are _________________________________________________________________
•
The _________________________________________ is an example of incomplete combustion
•
There are many ____________________________________ related to incomplete combustion
Example: Incomplete combustion of heptane, C8H18, a hydrocarbon in gasoline
Practice: Compare the complete and incomplete combustion of propane, C3H8.