Pseudo first order reactions

[305920501]

I understand that pseudo first order reactions are used to simplify a reaction by expecting one reactant has such a high concentration it will barely change and you can focus on the other reactions. When do we use this strategy, and how do we know when to use pseudo first order reactions? Why can't we just solve for a second/third order reaction rate in these cases?

[Austin Cortes 1E]

Pseudo-first order reactions are commonly used when one reactant is present in excess and its concentration remains nearly constant throughout the reaction. This strategy simplifies the rate expression, allowing us to focus on the kinetics of the limiting reactant. Pseudo-first order kinetics are preferred over solving for higher-order reactions in such cases because they simplify the mathematical analysis and are often more accurate when the excess reactant maintains a constant concentration.

[906112539]

I understand that pseudo first order reactions are used to simplify a reaction by expecting one reactant has such a high concentration it will barely change and you can focus on the other reactions. When do we use this strategy, and how do we know when to use pseudo first order reactions? Why can't we just solve for a second/third order reaction rate in these cases?

In summary, we use the pseudo-first-order approach when one reactant's concentration is significantly higher than others, simplifying the reaction kinetics. This strategy enhances experimental convenience and facilitates kinetic analysis, especially in cases where the true order of the reaction is difficult to ascertain.

You should use psuedo first order reactions when one reactant's concentration is much greater than the other. You use it when the reactant is in high excess amounts, we can treat the other reactants as the limiting factor in a reaction rate, because they will be consumed faster in the reaction. Another time you should apply pseudo first order is when there are multiple orders as well, since it helps you simplify to one reaction.

You could essentially solve for second/third order, but it would simplify to first order anyways since the reactant has a much higher concentration. If you choose to solve for second/third order, you're also more likely to make mistakes as compared to solving a simple first-order reaction.