Sodium only has one naturally occuring isotope, Na23 , with a relative atomic mass of 22.9898 u. A synthetic, radioactive isotope of sodium, Na22 , is used in positron emission tomography. Na22 has a relative atomic mass of 21.9944 u.

A 2.4698 g sample of sodium containing a mixture of Na23 and Na22 has an apparent "atomic mass" of 22.9551 u . Find the mass of Na22 contained in this sample.