Types of Chemical Reactions Synthesis, Combustion, Decomposition and Replacement
Types of Chemical Reactions
Synthesis, Combustion, Decomposition and Replacement
You can think of atoms as people getting together as couples...
Analogy Chemical Reaction
One person An ion or element
A couple A compound
Switching partners A replacement reaction
The Get Together…
Synthesis
Decomposition
Decomposition
Single Replacement Reactions
Single Replacement Reactions
Double Replacement Reaction
Double Replacement Reaction
Combustion
Combustion
How does this analogy break down?
People in Relationships Chemical Reactions
People can switch partners whenever they want
The ions or elements in a compound “switch partners” according to rules
We usually just think about one partner and one couple
In chemistry, we usually are dealing with billions of particles reacting at once
People don’t assume different states of matter
In double replacement reactions, there will be a change of state (a solid, liquid, or gas is formed)
People aren’t swimming in water
Displacement reactions generally happen in aqueous solutions
Let’s look at the reactions in more detailSynthesis
Decomposition
Single-Replacement
Double-Replacement
Combustion
Combustion
What are some types of combustion you are
familiar with?Every cell in your body is carrying out combustion
Combustion
Oxygen combines with a metal, non-metal, or compound
Creates a metal oxide, non-metal oxide, or 2 or more oxides
Releases energy – heat, light
Can be a slower process too…
Synthesis
2 or more reactants combine to make a product
Decomposition
A compound breaks down into two or more substances
Single Replacement
A metal replaces a hydrogen
A metal replaces another metal
We use an activity series to predict which metals are “stronger” and can knock out other metals from compounds
Activity SeriesThe most active metals are at the top. These will replace metals below them.
The halogens are also listed in order of most active at the top to least active at the bottom.
More active elements replace less active elements in single replacement reactions
Single Replacement Examples
2 AgNO3 + Cu Cu(NO3)2 + 2 Ag
Fe + Cu(NO3)2 Fe(NO3)2 + Cu
Zn + 2HCL ZnCl2 + H2
Double Replacement Reactions
Produces a precipitate, liquid or gas
All four of the ions switch partners
Aqueous solution
Double Replacement Examples
AgNO3(aq) + KCl(aq) AgCl(s) + KNO3(aq)
CaCO3(aq) + 2 HCl(aq) CaCl2(aq) + H2O(l) + CO2(g)
HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq)
How to identify a reaction
Steps to determine type
of reactionWrite the chemical
equation
Determine what is happening in the reaction
Use the table to identify the type of reaction
Check your answer by comparing the chemical equation to the generic equation
Be systematic – it will help you identify the reaction type and the products!
How to identify a reaction
Example: Identifying a reactionCaO (s) + CO2 (g) CaCO3 (s)
2 compounds are reacting to form one compound
This is a synthesis reaction
A + B AB
Example:
Solid calcium oxide and carbon dioxide gas react to produce solid calcium carbonate
Summary
The main types of reactions
Combustion – reaction with oxygen
Synthesis – two compounds or elements getting together
Decomposition – One compound splitting up
Replacement – Another ion moves in
Replacement Reactions: 2 types Single replacement – a
stronger cation steps in and replaces a weaker anion
Double replacement – 2 cations switch places, forming a precipitate, a liquid, or a gas
You try it!
Work on these examples together in pairs. Write the reaction Balance the equation Classify the reaction Be prepared to present your results on the board!
Magnesium and Hydrochloric acid form Magnesium Chloride and Hydrogen
Carbon Dioxide and Water form Carbonic Acid (H2CO3)
Silver Nitrate and Sodium Chloride form Silver Chloride and Sodium Nitrate
Heating sodium bicarbonate (NaHCO3) releases water and carbon dioxide and sodium carbonate
You try it!
Magnesium and Hydrochloric acid form Magnesium Chloride and Hydrogen: Mg + HCl MgCl + H2 (skeleton equation) 2Mg + 2HCl 2MgCl + H2 (balanced equation) Single replacement (reaction type)
Carbon Dioxide and Water form Carbonic Acid (H2CO3): CO2 + H2O H2CO3 (skeleton equation) CO2 + H2O H2CO3 (it’s already balanced!) Synthesis (reaction type)
You try it!
Silver Nitrate and Sodium Chloride form Silver Chloride and Sodium Nitrate AgNO3 + NaCl AgCl + NaNO3 (skeleton equation) AgNO3 + NaCl AgCl + NaNO3 (already balanced) Double replacement (reaction type)
Heating sodium bicarbonate releases water and carbon dioxide and sodium carbonate NaHCO3 Na2CO3 + H2O + CO2 (skeleton equation)
2NaHCO3 Na2CO3 + H2O + CO2 (balanced equation)
Decomposition (reaction type)