Water and oxygen are both required for iron to rust.
Besides moisture, identify the gas required for the corrosion of iron.
Rusting produces a compound with the formula Fe2O3\text{Fe}_2\text{O}_3Fe2O3. Write down the systematic chemical name of this compound, ensuring you specify the oxidation state of the iron.
Three students, Arthur, Beatrice, and Charlie, conducted an investigation into the rusting of three different iron bolts. They measured and recorded the mass of each bolt at the start of the experiment. After leaving the bolts exposed to moist air for one week, they measured the mass of each bolt again.
Their results are shown in the table below:
\begin{tabular}{|c|c|c|} \hline \textbf{Student} & \textbf{Mass of bolt before (g)} & \textbf{Mass of bolt after (g)} \\ \hline Arthur & 8.0 & 8.6 \\ \hline Beatrice & 2.0 & 2.4 \\ \hline Charlie & 5.0 & 4.8 \\ \hline \end{tabular}
Suggest one difficulty in obtaining an accurate mass of a rusted bolt at the end of the experiment.
Arthur concluded that his bolt rusted the most. Suggest a reason to justify his conclusion.
Beatrice argued that her bolt rusted the most. Explain how she could justify this argument using the data in the table.
Charlie's results show a decrease in mass. Explain why a decrease in mass indicates that an experimental error must have occurred.
Many iron objects are protected from rusting using a physical barrier to exclude oxygen and water.
Choose the most appropriate barrier from the box below for each of the two iron objects.
\begin{center} \textbf{plastic} \quad | \quad \textbf{grease} \quad | \quad \textbf{paint} \quad | \quad \textbf{tin plating} \end{center}
An outdoor steel garden railing:
________
A motorcycle drive chain:
________
Instead of physical barriers, iron can be protected by coating it with a thin layer of zinc. Even when this zinc coating is chipped or scratched, the underlying iron does not rust. State the term used for this method of protection and explain, in terms of reactivity, how it prevents iron from rusting.
