Types of Reactions

Now that you know how to balance chemical equations, let's look at classifying those reactions by type!

There are 6 general types: Synthesis, decomposition, single replacement, double replacement, combustion and neutralization.



However, in this blog, we will only cover the first 3 types. Read our next blog to learn about the last 3. :)

Ok. so..........synthesis. This is a reaction which combines 2 or more reactants (left side of arrow) to form a single product (right side of arrow)
If our 2 reactants were X and Y, and our product was Z, our synthesis equation would be

X + Y --> Z



That was easy. Now, the next one is similar. Decomposition is just synthesis, but backwards. Instead of having two reactants make one product, you have one reactant making two products. The equation would be

X --> Y + Z



For example, using real compounds, we would get...

NaCl --> Na + Cl

And that's all there is to it.

Now on to the most difficult of the three types so far: single replacement.
In this reaction, one element replaces an ion in an ionic compound.
Metals can only replace positive ions (cations) and non-metals can only replace negative ions (anions)



In a metal:
X + YZ --> Y + XZ
You can see that X replaces the Y, so Y is now the lone element, whereas X is now compounded with the Z.

In a non-metal:
X + YZ --> Z + XY
Here, X replaces the Z, because since X is a non-metal, it must replace a non-metal. And remember, if u have any of the HOFBrINCl elements that are going to be the "lonely" Z element in the product side, then you have to add a 2 to the formula, since it is diatomic.

To predict whether a specific single replacement will work, we use an activity series. This activity series show elements in order of reactivity. An element higher up the series can replace an ion below it on the table.



If the element is lower than the ion is replacing, then we say there will be no reaction (NR).

Here's a video to help you understand that.

Note that this video covers the other types, which we will cover in our next blog, so don't worry!

These are links to practice balancing and classifying reactions:
http://misterguch.brinkster.net/PRA020.doc
http://www.bishops.k12.nf.ca/science/1206/chem/reactiontypes.htm
http://chem.taysi.us/assignmentshandouts/reactions/ReactionTypesWS.pdf