Iron oxide contains two elements. Which?
Iron and oxygen.
Complete the following table:
| m(iron oxide) | m(iron) | m(oxygen) |
|---|---|---|
Try to calculate sums, differences, ratios, products ... . What do you see?
We see that the ratio of oxygen to iron remains constant: Deduce Proust's first law :
A chemical compound always contains exactly the same proportion (ratio) of elements by mass