Empirical Formula

Question

Empirical Formula

A sample of bismuth (Bi) of mass 4.870 g is heated in a crucible. The resulting bismuth oxide species (Bi_?O_?) has a mass of 5.428 g. Answer the following questions based on this information:

 

What is the mass of oxygen in the product?

How many moles of oxygen are in the product? 

How many moles of bismuth are in the product?

What is the empirical formula of the product?

 

Assuming the molar mass of the final product is 930 g/mol, what is the molecular formula of the product?

Answer 1

Determine the amount in grams of oxygen in the sample. Calculate the moles of oxygen and bismuth in the sample using the molar mass of both elements. Divide both values by the lowest moles (bismuth's) and find the empirical formula (Bi2O3). Divide 930 g/mol per the molar mass of the empirical formula. Get the ratio and multiply the empirical formula by that ratio.