Sodium only has one naturally occurring 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 1.3476 g sample of sodium-containing a mixture of Na23 and Na22 has an apparent "atomic mass" of 22.9501 u. Find the mass of Na22 contained in this sample.