According to Wikipedia:

Chemical reactions occur faster in the presence of a catalyst because the catalyst provides an alternative reaction pathway with a lower activation energy than the non-catalyzed mechanism. In catalyzed mechanisms, the catalyst usually reacts to form a temporary intermediate, which then regenerates the original catalyst in a cyclic process.

Since catalysts react in intermediate reaction and hence in the rate-determining step, is it possible that they appear in the kinetic rate equation?

If so are there some examples?

Edit: For more clarity I encountered this doubt in a true or false question which went like this:" Catalyst can appear in kinetic rate equation".

Edit 2: As told in the comments, another similar question says specifically that catalyst are not included in rate equations, but the question I encountered says it might sometimes. So there is some irregularity in my question which seems highly unlucky to me as I have read some examples like hydrolysis of esters where rate is directly proportional to H+ concentration.

Am I wrong?

  • $\begingroup$ But that significantly says that catalyst is not included in rate equation. But the question I encountered says it might sometimes? Also I have seen that in hydrolysis of esters, rate of reaction is proportional H+ concentration? $\endgroup$ May 11 '20 at 16:04
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    $\begingroup$ In some cases the catalyst concentration will disappear in simplified rate equations especially when using the steady-state assumption to generate tractable rate equations. But some reactions are not well modelled by that assumption so the catalyst might need to appear in the equation. $\endgroup$
    – matt_black
    May 11 '20 at 16:26