When iron rusts and forms iron oxide, the iron oxide has more mass than the iron. Which statement correctly explains this observation?

The increase in mass observed when iron rusts and forms iron oxide can be explained by the combination of iron with oxygen from the air.

The observation that iron oxide has more mass than iron when iron rusts can be explained by the chemical reaction that occurs during the process. When iron reacts with oxygen in the presence of water or moisture, it undergoes oxidation, resulting in the formation of iron oxide (rust). This chemical reaction can be represented as follows:

4Fe + 3O2 + 6H2O → 4Fe(OH)3

In this reaction, iron (Fe) combines with oxygen (O2) to form iron(III) hydroxide (Fe(OH)3). Iron(III) hydroxide is the main component of rust.

Now, let's analyze the reactants and the products of this reaction.

- Reactants:
1 molecule of iron (Fe)
3 molecules of oxygen (O2)
6 molecules of water (H2O)

- Products:
4 molecules of iron(III) hydroxide (Fe(OH)3)

Based on the balanced chemical equation, it is clear that the formation of iron(III) hydroxide involves the combination of multiple atoms of oxygen and water with the iron atoms. This additional combination leads to an increase in the total mass of the products compared to the reactants.

Therefore, the correct statement to explain this observation is: "During the process of iron rusting, the formation of iron oxide involves the combination of extra atoms of oxygen and water with the iron atoms, resulting in a greater mass for the iron oxide compared to the original mass of iron."

If you tried to copy and paste your choices, that does not work.

Without seeing them, the O2 from the air joins its mass to the iron mass to make iron oxide. That oxygen mass adds to the Fe mass.