question related to chemical kinetics?

Question

zero oder reaction is the one whose rate is independent of concentration rite??
now a order of a reaction can be negative rite?
so now here is a reaction
A+B----->C
now if if the rate law is
rate=k[A]^-1.[B]^1
now order of the reaction is 0.
but if i change conc of a the rate will also change rite.
then how a can it b a o order reaction.
plz clear my doubt

hey c_f15h
i agree wid u but wat if i only double A or double only B.
that is change conc of only one of the reactant

Answer 1

The order of a reaction is determined experimentally. It is zero order OVERALL because overall order is the summation of the orders of all of the reactants. I have no idea what that overall order is EVER used for - other than giving you the overall order and then not giving you one of the reactants and making you figure it out.

I have never seen anything ever done with the overall order that you speak of.

The point is - the rate depends on orders of the reactants. If you double the concentration of B, you will see an effect on the rate, and if you change the concentration of A you will see an effect on the rate.


Make up numbers and plug them in for yourself. Make up a number for k. Then plug 1 M in for A and B. See what the rate is. Then using the SAME k value, change the concentration of A to 2M and keep B at 1M, what is the new rate. Then, using the SAME value for k, put A at 1M and B at 2 M, calculate the rate. As long as you use the SAME value for k, you are just investigating the rate law.

Answer 2

A negative first order on A means that when you double A's concentration, the rate would be cut in half. However, because B is first order, it means that when its concentration doubles, the rate would also double.

Therefore, the one-half from A and the double from B cancel out (1/2 * 2 = 1). Therefore, it is exactly the same as 0 order, which is the overall reaction rate.

Answer 3

Since overall rate is 0, that will prevail.