An oxide of an element has the formula #"X"_2"O"_7# and contains 50.45 % oxygen. What is the atomic mass of the element?
The atomic mass of the element is 55.00 u.
The formula of the oxide is X₂O₇.
Assume 100 g of the oxide.
Then you have 50.45 g of O and 49.55 g of X.
Moles of O = 50.45 g O ×
Moles of X = 3.153 mol O ×
Molar mass of X =
The atomic mass of X is 55.00 u.