Molecularity

[Yun Su Choi 3G]

Does the molecularity of the slow elementary step always match that of the overall rate law?
Or can differ when intermediates are involved in the reactant side of the slow step?

[Kyle Walsh 2J]

Hi! I believe that the molecularity of the slow elementary step will always exactly match the rate law, as both the molecularity and rate law are only concerned with the species that affect the reaction in any given step. Therefore, I'm pretty sure intermediates would be ignored in both. Hope this helps!

[Jerry_T]

The molecularity is the number of species in an elementary step (i.e. the number of collisions) which has to agree with the order of the rate law. (Lecture 24)

[Vanessa Wiratmo 3k]

Hello,

The molecularity will match/agree with the rate law. The kinetic order of any elementary reaction or reaction step is equal to its molecularity. Molecularity refers to the number of particles that collide in a specific step.

[Maggie Messer 1A]

The Molecularity will always match the overall rate law. Molecularity is the number of particles in the elementary step.

[Andrewtrung Le 3A]

Hello!

Because the overall reaction is limited by the slow step, the molecularity of the slow step will match the overall rate law.

[905740390]

the molecularity of the slowest step will match the overall rate.

[105784203]

Does the molecularity of the slow elementary step always match that of the overall rate law?
Or can differ when intermediates are involved in the reactant side of the slow step?

yes and no

[Abby Citro 2A]

The molecularity of the slow (elementary) step will match the overall rate law.

[Jeffrey Vo 2A]

hi yun,

molecularity will always be the same as the slowest step, and this is the limit of the molecularity that matches the overall rate law as stated in lecture.

[705676154]

Hi:) the Molecularity always matches the overall rate!

[405716590]

it always matches the overall rate

[205756817]

the Molecularity of a slow step reaction will always match the overall molecularity of the chemical reaction. This is because the slowest step is always the rate determining step of a reaction and the kinetics and the rate of the reaction will always depend on that.

[405690892]

To clarify, the slow rate order will be the overall rate order of the reaction mechanism?

[Student805]

the molecularity of the slow step will always match the overall order of the reaction, because the slow step determines the order

[Eleanor_C_1I]

I believe molecularity of a reaction would have to agree with the slowest step. Molecularity reflects the number of species (reactants) involved in an elementary step, so while I think it is possible that each step might have different molecularity, the rate determining step will have the same species that are in the overall rate - as the slow step is the rate-limiting step - so they should be the same.

[Briana Gilman 1F]

the overall resulting order of the reaction will match the molecularity of the slow step because the slow step determines the order of the reaction. intermediates cannot directly contribute to the overall rate law but they do indirectly contribute because if your rate law has an intermediate, replace the intermediate in the rate law with the reactants that made up the intermediate (which was a product) in the previous reaction

[Briana Gilman 1F]

the overall resulting order of the reaction will match the molecularity of the slow step because the slow step determines the order of the reaction. intermediates cannot directly contribute to the overall rate law but they do indirectly contribute because if your rate law has an intermediate, replace the intermediate in the rate law with the reactants that made up the intermediate (which was a product) in the previous reaction