Question

Given a `60*"amu"` mass of carbon atoms, how many carbon atoms are there?

Answer 1

A `60*"amu"` mass of `""^12C` contains 5 carbon atoms........

Explanation:

A single `""^12C` atom contains 6 nuclear protons, and 6 neutrons, and to a first approx. this represents the mass of the atom. Five `""^12C` atoms should thus have a mass of `60*"amu"`.

This use of mass to express the number of atoms or the number of molecules, is enshrined by our use of `"Avogadro's number"`, and the idea of `"equivalent mass"`. This is one of the most important things you can learn as you study chemistry.

What is the actual mass of `6.022xx10^23` individual `""^12C` atoms; what about the mass of `6.022xx10^23` `""^13C` atoms?