Why does 1 amu = 1 g/mol?

1 Answer
Mar 26, 2018

Answer:

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