# Rate constant from rate-concentration graph

Watch
Announcements
#1
Why can't you obtain the rate constant from the gradient of a rate-concentration curve of a second-order reaction but you can via the gradient of a rate-concentration curve of a first-order reaction? I know that for the second order reaction the rate constant would change although I'm not sure how this makes the method wrong assuming the rate constant can change 🙂

Does the value of the rate constant have to be constant? 😂
0
2 years ago
#2
(Original post by Freedom physics)
Why can't you obtain the rate constant from the gradient of a rate-concentration curve of a second-order reaction but you can via the gradient of a rate-concentration curve of a first-order reaction? I know that for the second order reaction the rate constant would change although I'm not sure how this makes the method wrong assuming the rate constant can change 🙂

Does the value of the rate constant have to be constant? 😂
The rate constant is errr constant. It only changes with temperature.

Rate = k[A]x

The second order reaction gives a curve.

Rate = k[A]2

You can plug in values of rate at any given concentration to find the rate constant.

The first order graph is a straight line. Once again simply plug in values to find 'k'.
0
#3
So why do you need to plot a graph of rate against concentration squared in order to find k for a second order reaction? Is it just because tangents are unreliable? 😄
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Do you have the space and resources you need to succeed in home learning?

Yes I have everything I need (326)
55.82%
I don't have everything I need (258)
44.18%