Chapter 2, Problem 50AP

A sample of a substance with the empirical formula ${\text{XBr}}_{\text{2}}$ weighs 0.5000 g. When it is dissolved in water and all itsbromine is converted to insoluble AgBr by addition of anexcess of silver nitrate, the mass of the resulting AgBr isfound to be 1.0198 g. The chemical reaction is

${\text{XBr}}_{\text{2}}+{\text{2AgNO}}_{\text{3}}\to \text{2AgBr}+\text{X}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$

(a) Calculate the molecularmass (that is, formula mass)of ${\text{XBr}}_{\text{2}}$ .

(b) Calculate the atomic mass of X and give its name andsymbol.