What does first-order and second-order mean?

[305597516]

Hello, I am still really confused on what exactly the number of the order means. I know that they have to do with the exponent of the concentration for the rate law equation, but contextually, I'm not sure what the professor means when he just says that they show the mechanism.

[Alexis Shen 2G]

Hi! The order number for a specific molecule/substance/etc. is the number of that thing that needs to collide at the same time for the overall reaction to take place. So if H2O had a second order, two H2O would need to collide at the same time to make something. Then if the overall order of a reaction is like 3, so two H2O and one O2, then all three of those would need to meet at the same time. Hope that helps!

[A 3F]

The order of the reaction tells us how many species' concentrations the reaction depends on. For example, in a first-order reaction, the reaction only relies on the concentration of one molecule. In a second-order reaction, the reaction would rely on the concentration of two reacting molecules. This could be between two different molecules, [A][B], or two of the same molecules, [A]^2.

[MattDixon3A]

First order reactions are reactions in which the rate of reaction is dependent on the concentration of one reactant, and second order reactions have their rate of reactions dependent on either a.) two reactants to the first order or b.) a reactant to the second power. This means that in a first order reaction, if we double the reactant, the rate of the reaction also doubles. In the case of a second order reaction, doubling the reactant concentration will quadruple the rate of reaction. I hope this helps clarify a bit!

[Lulu Almoshawah_2K]

in first order reactions the reaction rate depends on the molar concentration of one of the reactants that's involved in the reaction whereas in second order reactions the rate of reaction depends on the molar concentration of two of the reactants or the second power of one reactant that's involved in the reaction :)