CHEMISTRY COMMUNITY

In this question why is it that chlorine is an intermediate when it's produced as an atom in reaction 1 but reacts as an ion in reaction 2?

Chlorine is an intermediate because it is produced in step 1, but it is used as a reactant in step 2; therefore, they cancel out, and the overall reaction does not include it.

I see what you're saying here, and I originally included them in the overall reaction as well because an atom and an ion of the same element can behave very differently. Maybe they forgot the - for the reactant side Cl?

Another perspective to take on intermediates, is that are not present in the reactants of the first step and the products of the last step. Therefore Intermediates are produced by an elementary reaction but consumed in another one.

intermediates get immediately used up, so in a sense its like they're not even there in the first place. their existence is temporary.