What are the small elements over the equilibrium symbols?

[Jenaye Brelland 2I]

I was reading a forward reaction and it had a small Fe above the arrow? What does that mean? Is the reaction dissolved in Fe? Or the reaction is caused by adding Fe? Is Fe the catalyst for the reaction?

[JaesalSoma1E]

I think catalysts are written above the arrow because they aren't taking part in the reaction but they are still present. So in this case, Fe would be the catalyst if I'm not wrong.

[Andreas Krumbein 1L]

Catalysts are written above the arrow if one is present, since they do not contribute to the reaction as either a reactant or a product, but are still important to the reaction nonetheless by providing the right conditions for the reaction of occur. The catalysts are not used up after the reaction takes place so they cannot be considered a reactant, nor are they a product.

[Eliot Kagan 2G]

Yes, I would also assume that the elements above are catalysts of the reaction. They likely affect the reactants in a way that allows the chemical reaction to occur while not being consumed by the reaction.

[Annie Liang 3D]

Yes, catalysts are written above the arrow since it is neither a reactant or product. They help speed up a reaction without being used up or produced.

[Pranav Daggubati 3C]

These are catalysts, which are need for the reaction to proceed but aren't consumed. Sometimes, you'll see a capital delta symbol, which means that heat is being infused to make that reaction go forward.