How do you determine the average weighted isotopic mass of Carbon?

Question

Wyatt Atkins · Accepted Answer

Well, first you must quote the percentage isotopic masses of the common isotopes.

According to this site, #""^12C# has a 99% abundance, and #""^13C# has a 1% abundance (there are other isotopes, but these are the most abundant). The weighted average is #(12xx0.99)# #+(13xx0.01)# #"amu"# #=# #12.01# #"amu"#. The #""^13C# isotope is a very important nucleus inasmuch as #""^13C{""^1H}# #"NMR spectroscopy"# can be routinely performed.

Wyatt Atkins · Answer

undefined The calculation for the average weighted isotopic mass of carbon would be: $$ (12.00000 \times 0.9893) + (13.00335 \times 0.0107) = 12.011 $$ This would yield the average weighted isotopic mass of carbon, which is approximately 12.011 atomic mass units (AMO). This calculation takes into account the relative abundance of each carbon isotope (carbon-12, carbon-13, and carbon-14) and their respective atomic masses. For instance: - Carbon-12: Atomic mass = 12.00000, Abundance = 98.93% - Carbon-13: Atomic mass = 13.00335, Abundance = 1.07% - Carbon-14: Atomic mass = 14.00324, Abundance is very low and negligible for most calculations.