You take three compounds, each consisting of two elements (X, Y, and/ or Z) and decompose them to their respective elements. To determine the relative masses of X, Y, and Z, you collect and weigh the elements, obtaining the following data:

Elements in Compound                                                          Masses of Elements

1. X and Y …................................................................         X = 0.4 g, Y = 4.2 g

2. Y and Z ….................................................................         Y = 1.4 g, Z = 1.0 g

3. X and Y ….................................................................        X = 2.0 g, Y = 7.0 g

What are the assumptions needed to solve this problem?

What are the relative masses of X, Y, and Z?

What are the chemical formulas of the three compounds?

If you decompose 21 g of compound XY, how much of each element is present?