# How do I find the ratios between the number of moles of each element to determine the formula of the compound?

You can use the mole ratio of elements in a compound to determine the empirical formula of a compound.

For example - analysis of a sample of water would reveal that the number of moles of hydrogen atoms present in the sample is twice the number of moles of oxygen atoms in the sample. This lets us conclude that the empirical formula of water is ${H}_{2} O$ which is also the formula of the compound.

*Note - sometimes the empirical formula will not always be the chemical formula for a compound. For example, hydrogen peroxide has an empirical formula of HO, but a chemical formula of ${H}_{2} {O}_{2}$.

Here is a video which shows how to calculate an empirical formula from experimental data for a hydrocarbon compound.

Video from: Noel Pauller

And here is a video which discusses how empirical formulas

Video from: Noel Pauller

Hope this helps!