Chemistry’s Most Important Number

Added: 2026-05-19

[00:00:00]Avogadro's number. It allows us to start to do quantitative calculations in chemical reactions. Because as you know, everything's made of atoms, but atoms are so small that you can't really individually count them. So, the problem is when we do a chemical reaction in a lab, we want to measure out so much of material A and so much of material B and react them together and figure out how much of material C is going to result from the chemical reaction. But when we measure things in the lab, we're always measuring them in terms of their mass in terms of grams. Grams of carbon, grams of oxygen. How much carbon dioxide in grams will be formed at the end of that reaction? Avogadro's number is the the tool that we need to join grams, which is something we measure in mass, with molecules and atoms, which is what we know everything is made of.

[00:00:50]Let me say that one more time.

[00:00:51]Avogadro's number is the tool to join the microscopic, counting atoms and molecules, with the macroscopic, which is measuring grams of a substance, okay?

[00:01:03]Joining those two ideas together, we have to do it in order to calculate anything. Learn anything at mathandscience.com.