Understanding different types of chemical reactions is a key skill in Year 12 Chemistry. Once you learn the basics, it can be quite simple!

Let’s go over the main types of reactions you will see:

1. Synthesis Reactions: This type happens when two or more substances come together to make one new substance. For example, when you mix hydrogen and oxygen, you get water:
   $2H_2 + O_2 \rightarrow 2H_2O$

2. Decomposition Reactions: In this case, one compound breaks apart into two or more simpler substances. A good example is when heat is applied to calcium carbonate, which breaks down into calcium oxide and carbon dioxide:
   $CaCO_3 \rightarrow CaO + CO_2$

3. Displacement Reactions: Here, one element takes the place of another in a compound. For instance, if zinc displaces copper in copper sulfate, it looks like this:
   $Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$

4. Combustion Reactions: These reactions occur when a substance, usually made of carbon and hydrogen, burns in oxygen, creating carbon dioxide and water. For example, when you burn methane, the reaction looks like:
   $CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$

When you balance these reactions, your goal is to make sure the number of each atom is the same on both sides of the equation.

Start by counting how many atoms of each element you have before and after the reaction. Then, change the coefficients (the numbers in front of the substances) until both sides match up.

It may take some practice, but as you get used to the patterns and steps, it will become much simpler!