The reason moles are important can be illustrated this way: what if you had some carbon and some hydrogen? You might want each carbon atom to buddy up with one hydrogen molecule.
How do you make sure each carbon atom and each hydrogen molecule is paired and no one is left out? You can’t just put together equal mass of each one, because they weigh different amounts. What you want to do is add equal moles of each. A mole is 6.022 × 10^23 of the basic chemical entities that make up each.
Add 12 grams of carbon and 2 grams of hydrogen and you will have equal numbers of each: 1 mole.
