# What are some common mistakes students make with chemical equations?

May 30, 2014

Perhaps the most common mistake is mistaking diatomic molecules as being already balanced in a chemical equation.

Here's an example of what I mean:

${C}_{6} {H}_{12} {O}_{6} \to {C}_{2} {H}_{5} {O}_{6} + C {O}_{2}$

Balanced it's

${C}_{6} {H}_{12} {O}_{6} \to 2 {C}_{2} {H}_{5} {O}_{6} + 2 C {O}_{2}$

Students tend to forget that $C {O}_{2}$ needs to be balanced - the fact that it has a familiar chemical formula doesn't help.

It is also really common to forget that $C {O}_{2}$ has two atoms of oxygen - this is an essential piece of knowledge when balancing equations. It does not mean that there are two molecules of $C {O}_{2}$, it merely means there are two atoms of oxygen present in the molecule.