# How amu is equal to Molar Mass . Must S33

## Main Question or Discussion Point

How amu is equal to Molar Mass ..... Must S33

Hey fellows I want to know that how amu is equal to molar mass of element. I think it's not possible unless weight of atoms of all elements is same. And by doing so it will mean that as Carbon-12 has molar mass of 12g and 12 amu then (if weight of all atoms are equal) one gram of any substance will be equal to one amu. Please explain. ( I am really tired of Wikipedia's complicated explaination.)

Borek
Mentor

amu is a unit selected in such a way that molar mass in grams equals (numerically) mass of the molecule (atom) expressed in amu. That's all.

I think it should need more explanation.

Ygggdrasil
Gold Member
2019 Award

It all has to do with the fact that 6.02x1023 amu = 1g.

Here's a simpler analogy. A pound (Imperial weight unit) is equal to roughly 2 kg. Therefore, let's define a "gopher" as two of something. Now, let's say we have some rocks that each have a mass of 1kg. A "gopher" of rocks (two rocks) will have a mass of 2 kg or approximately one pound. Thus the mass of an individual rock in kg (1) is equal to the weight of one "gopher" of rocks in pounds (also 1).

Similarly, the mass of one atom in amu will be equal to the mass of a mole of that atom in grams simply because of the conversion between units above.

That helped until I found the meaning of of Gopher.

Borek
Mentor

Check the meaning of mole.

Yeah . You was also post same! thanks.