The atomic mass of radium (Ra, a new radioactive element) was measured by Marie Curie as a part of her Ph. research (Radioactive substances, 1903).

The atomic mass of radium (Ra, a new radioactive element) was measured by Marie Curie as a part of her Ph.D. research (Radioactive substances, 1903). She knew that the faormula for radium chloride is RaCl2 becuase radium is in the same family as barium. In one experiment, 0.09192g of pure RaCl2 was dissolved and treated with excess AgNO3 to precipitate 0.08890g of AgCl. How many moles of Cl- were in RaCl2? Determine the atomic mass from this measurement.