Why does 1 amu = 1 g/mol?

1 Answer
Nam D.
Mar 26, 2018

Due to the definitions...

Explanation:

The mole is defined as the number of particles in 12 \ "g" of carbon-12, known as ""^12C. So, we say that in one mole of carbon-12, the sample has a mass of 12 \ "g".

In other words,

"mass of carbon-12"=12 \ "g/mol".

Still with me? Good.

Now, we also know that the mass of a single carbon-12 atom is exactly 12 \ "amu", as it is an isotope.

And so,

"mass of carbon-12"=12 \ "amu/atom"

Combining, we have:

12 \ "amu/atom"=12 \ "g/mol"

=>1 \ "amu/atom"=1 \ "g/mol"

Therefore we just proved that an atomic mass unit is the same thing as grams per mole. Hope this helps!

For a further explanation, visit:

https://chemistry.stackexchange.com/questions/13764/amu-and-g-mol-relation

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