2
$\begingroup$

I found out there are two definitions of relative atomic mass $A_\mathrm r$.
First definition is $A_\mathrm r$ is the mass of 1 atom of an element relative to 1/12 the mass of carbon-12 atom. It can be found in any chemistry school textbook.
Second definition is what I just found and dont understand. It states $A_\mathrm r$ is the mass of 1 mole of atoms relative to 1 mole of carbon-12 atoms.
Can you kindly explain second definition with examples?

$\endgroup$

1 Answer 1

2
$\begingroup$

These are all mathematically identical. Here’s why:

$$\frac{\text{mass of one atom}}{\frac1{12}\text{ mass of one atom of }\ce{^12C}}\\=\frac{\text{mass of one atom}\times N_\mathrm{A}}{\frac1{12}\text{ mass of one atom of }\ce{^12C}\times N_\mathrm{A}}\\=\frac{\text{mass of one mole of substance}}{\frac1{12}\text{ mass of one mole of }\ce{^12C}}$$

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.