Mole Ratios
When you are completing mole ratios, you always need to start with a balanced chemical equation. Once you have a balanced chemical equation, you can use the ratio to predict how much product will form from reactants, or how much reactant is needed to produce a specific amount of product. Watch the following video to see how this is done using mole ratios.
https://youtu.be/1XQyNet6bI
Watch the following video from 0:00 to 6:00 to learn more about mole ratios and how to use mole ratios in stoichiometry. If you need additional review, please watch the video further.
Molar Mass
The atomic mass of an element is the weight in grams of 1 mole of atoms. This is also called the molar mass. For example,

The molar mass is used to convert between grams and moles. Watch the following video to learn about how to do these types of conversions.
https://youtu.be/zWzAT54pPI
For additional practice with solving mass to moles stoichiometry problems, click on the button below labeled "Moles to Mass Practice Problems."
Percent Composition By Mass
Watch the following video for how to determine the percent composition by mass.
Empirical Formulas and Molecular Formulas
Watch the following video to learn about the empirical formula and the molecular formula.
https://youtu.be/wnRaBWvhYKY
Watch the following video to learn about how to calculate the empirical formula of a compound.
https://youtu.be/xjnfga0BwCs