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Types of Chemical Reactions
Chapter 11 Section 2
Objectives: SWBAT:
Identify the type of reaction (synthesis/combination, decomposition, single replacement, double replacement, or combustion) by looking at the general patterns of these equations
You will accomplish this through completing today’s POGIL activity and actively participating when it is time for group discussion.
How will this POGIL activity work? You will be in your groups You will see a stop sign which
means to stop I will time each part so you know how much
time you have to finish up the section I will roll a dice to determine which group
AND which person in the group will answer the key idea questions and possibly other questions.
Why classify chemical equations?
Let’s check out what our POGIL says!
Combination Reactions (Synthesis)
Two or more reactants come together to form one product
Keep an eye out for… Two or more reactants One product
A + B AB Example: 2Mg (s) + O2 (g) 2MgO (s)
+
Like the start of a dance… Synthesis (Combination) is like when two
people come together to start a dance…
Decomposition Reactions A single compound breaks down into two or
more simpler products Keep an eye out for:
One reactant Two products
Require some form of energy to break the initial compound
XY X+ Y Example: 2HgO (s) 2Hg (l) + O2 (g)
+heat
heat
heat
Like the end of a dance… Decomposition is like when two people are
done dancing and step apart from one another.
Single Replacement Reactions One element replaces a second element in a
compound Keep an eye out for
Products and reactants consisting of one element and one compound
Switch of one element for another in a compound C + DE CE + D
Example: Zn (s) + Cu(NO3)2 (aq) Cu (s) + Zn(NO3)2 (aq)
+ +
Like when someone cuts in… Single replacement is when one ion taps the
shoulder of the other ion to cut into the dance…
Activity Series
Lists metals in order of reactivity
If a metal is more reactive (i.e., higher up on the activity series) it will replace another metal
Allows us to predict our products!
Halogens A halogen can replace a halogen The activity decreases top to bottom
down group 7A Thus, if one halogen is above another
halogen, it can replace the halogen below it but none above it.
As with the Activity Series…more on this later when we get to predicting products!
Double-Replacement Reactions Chemical change involving an exchange of positive ions
between two compounds Generally take place in aqueous solutions Can only occur if…
One of the product is only slightly soluble and forms a ppt One product is a gas One product is a molecular compound
Keep an eye out for... The above products Switching of two cations
AB + XY XB + AY Example: Na2S (aq) + Cd(NO3)2 (aq) CdS (s) + 2NaNO3
People Switch Partners! Double replacement is like when two dance
partners switch.
Combustion Reactions Reaction of a carbon-based compound with
oxygen that produces carbon dioxide and water vapor
Used to produce energy Like in power plants
Keep an eye out for: Production of CO2 (g) and H2O (g) Reaction with O2 (g)
C2H2 (g)+ O2 (g) CO2 (g) + H2O (g)
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