Here is one example of each category which are then solved below:
1) LiCl + O2 --->Example #1How to figure out the right (or product side):(1) Ask yourself what type of decomposition produces these products:
2) Na2O + CO2 --->
3) SO3 + H2O --->
4) N2 + H2 --->
LiCl + O2 are the products of a chlorate decomposing.
Chlorate is always ClO3¯So the final answer looks like this:
Li is plus one
LiCl + O2 ---> LiClO3Example #2How to figure out the right (or product side):(1) Ask yourself what type of decomposition produces these products:
Na2O + CO2 are the products of a carbonate decomposing.
While there are many , they all fall into at least one of four broad categories: synthesis reactions, decomposition reactions, single displacement reactions, or double displacement reactions.
Written using generic symbols, it is usually shown as:
A + B ---> ABThese are some examples:
Mg + O2 ---> MgONotice that two elements are combining in each example.
H2 + O2 ---> H2O
K + Cl2 ---> KCl
Fe + O2 ---> Fe2O3
The hallmark of a synthesis reaction is that a more complex product is formed from the reactants. One easy-to-recognize type of synthesis reaction occurs when two or more elements combine to form a compound. The other type of synthesis reaction happens when and element and a compound combine to form a new compound. Basically, to identify this reaction, look for a product which contains all of the reactant atoms.
Here is one more category of decomposition reactions:
CaO + H2O ---> Ca(OH)2The first two substances are metallic oxides and the last two are nonmetallic oxides.
Na2O + H2O ---> NaOH
N2O5 + H2O ---> HNO3
P2O5 + H2O ---> H3PO4
1) Direct union of two elements will produce a binary compound.
2) Metallic oxides and carbon dioxide react to produce carbonates.
Here's another example of a synthesis reaction:
H2 + O2 ---> H2O2This happens to be a reaction that can never take place.
Carbonate is always CO32¯So the final answer looks like this:
Na is plus one
Na2O + CO2 ---> Na2CO3Example #3How to figure out the right (or product side):(1) Ask yourself what type of decomposition produces these products:
SO3 + H2O are the products of an acid decomposing.
Here's an example:
CO2 + H2O ---> C6H12O6 + O2You might recognize this as the photosynthesis equation.
In SO3 the S has an oxidation number of +6H has its usual value of +1 and O has its usual value of -2So the final answer looks like this:
SO3 + H2O ---> H2SO4If this oxidation number business is unknown to you, the only other way is to memorize a set of reactions.
Synthesis can also be two compounds making a more complex compound (or a compound and an element joining together) as in these examples:
CaO + CO2 ---> CaCO3Notice how, in every case so far, there is only one substance on the right-hand (product) side.
Na2O + CO2 ---> Na2CO3
KCl + O2 ---> KClO3
Ba(ClO3)2 ---> BaCl2 + O2
Example #4How to figure out the right (or product side):(1) Ask yourself what type of decomposition produces these products:
N2 + H2 are the products of a binary compound decomposing.
Be sure to count the number of atoms in both the reactants and products. Sometimes when a chemical equation is written, "extra" information is given that may make it hard to recognize what is going on in a reaction. Counting numbers and types of atoms makes it easier to identify reaction types.