Question

Consider two samples of carbon. One is a sample of one mole of carbon atoms obtained from the environment (i.e. isotopes are present according to their natural abundance), and the other is a sample of one mole of carbon-12 atoms (i.e. isotopically pure). Which sample has a higher mass, or are they both the same mass? Justify your answer, either with words or mathematically

Answer 1

Answer:

The sample obtained from the environment has a higher mass

Explanation:

A simple way to put the answer is that the element carbon -as found in nature- has a molar mass of 12.0107 g/mol, because there are a few isotopes of 14C and 13C; and the molar mass is an expression of the isotopes' natural abundance.

So 1 mole of carbon obtained from the environment would weigh 12.0107 g, while a sample of isotopically pure carbon would weigh 12.0000 g.