Look at the notes below about the Haber process. What is iron acting as in this process?

In the Haber process, iron acts as a catalyst. This means it speeds up the reaction between nitrogen and hydrogen to form ammonia, without being consumed in the process.

Without the notes on the Haber process, it's difficult to provide a specific answer. However, in the Haber process, which is used to manufacture ammonia from nitrogen and hydrogen, iron is typically used as a catalyst. This means it speeds up the reaction without being consumed in the process.