catalyst

[Vuong_2F]

how can determine if a species is a catalyst?

[Jessica Castellanos]

When given a reaction mechanism, the catalyst will be in the reactants side, will be used up, and then produced again by the end, so that in the overall reaction the catalyst isn't used up.

[MaggieHan1L]

It is present at the beginning and reappears at the end as opposed to an intermediate which forms and disappears during the reaction

[RasikaObla_4I]

catalysts are used up and then reformed so they start in the reactants of one reaction and are reformed in the products of another reaction.

[Orrin Zhong 4G]

A species is a catalyst if it exists at the start of the reaction, then gets used up by the reaction, but gets reformed at the end of the reaction.