A chemistry student determined the empirical formula for tungsten oxide (W
xO
y). To do so, he heated tungsten with oxygen in a crucible. The data that he recorded are shown below:
| Weight of crucible | 11.120 g |
| Weight of tungsten | 8.820 g |
| Weight of crucible and product | 22.998 g |
What is the empirical formula of tungsten oxide?