Determining Rate Law of a Reaction With Multiple Reactants

[Eliana Carney 3E]

Hey guys!
In Lecture #24, Dr. Lavelle explained that if you have a reaction with multiple reactants, you can determine the rate of the reaction by making the concentration of one reactant very small compared to the others. I understand this experimental process for finding the rate law, but me question has to do with lowering the concentration of one reactant. In a sense, by lowering the concentration of a reactant, are you making it into a limited reactant? My thought process behind this is by making a reactant into a limited reactant, the other reactants won't have an effect on the reaction because their concentration will change so little as a result of having the limited reactant. If someone could let me know if this idea is headed in the right direction or explain why it's not correct, that would be appreciated!

[Emily Vu 1L]

Yes, you are on the right track Eliana. In our experiment, if we have one reactant at a low concentration then when a reaction proceeds, the change in concentration for the other reactants will be so small we can neglect it.

[Eliot Kagan 2G]

Yes. I think it is also due to the fact that the other elements will be so large that their changes will be negligible. If the other two elements are negligible, we can determine that the change in its rate is only based on the element with the small concentration.