order of reactions
Moderators: Chem_Mod, Chem_Admin
-
- Posts: 52
- Joined: Wed Nov 21, 2018 12:19 am
-
- Posts: 104
- Joined: Sat Aug 17, 2019 12:18 am
Re: order of reactions
Normally, the order of the reaction must be determined empirically. Often, empirical data is given in the question which you may manipulate to determine the order of the reaction.
Re: order of reactions
Use the method of initial rates to determine the reaction order with respect to each of the reactants. Then sum those orders to obtain the overall reaction order. Alternatively, one can determine the overall reaction order from the plots of [A] vs time, ln[A] vs time, and 1/[A] vs time (the integrated rate laws) for experimental time/concentration data. Provided that the reaction is either zero, first, or second order, the most linear plot corresponds to the reaction order. A linear [A] vs time plot indicates a zero-order reaction, a linear ln[A] vs time plot indicates a first order reaction, and a linear 1/[A] vs time indicates a second order reaction
-
- Posts: 101
- Joined: Fri Aug 30, 2019 12:17 am
Re: order of reactions
Reaction rates are determined empirically by changing one reaction concentration at a time and observing the effect on the reaction rate. If you double the initial concentration of A and the rate does not change, A is zero order. If the rate doubles, A is first order. If the rate quadruples, then A is second order.
It can also be determined graphically. If the concentration of A vs time is linear, then A is zero order. If ln([A]) vs time is linear, it's first order. If 1/[A] vs time is linear, then A is second order.
It can also be determined graphically. If the concentration of A vs time is linear, then A is zero order. If ln([A]) vs time is linear, it's first order. If 1/[A] vs time is linear, then A is second order.
Re: order of reactions
Another good way to determine whether a reaction is in the zeroth, first, or second order is to look at the units of k, the rate constant. If the units of k is M/s, it is in the zeroth order; if k is 1/s, it is in the first order; if k is 1/M*s, it is in the second order.
Return to “Zero Order Reactions”
Who is online
Users browsing this forum: No registered users and 3 guests