Deriving these Equations

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

Payton Schwesinger 1J
Posts: 45
Joined: Fri Sep 29, 2017 7:04 am

Deriving these Equations

Does [A] always mean [A] initial? Or does it have to be explicitly shown? ( [A]0)

Lorie Seuylemezian-2K
Posts: 62
Joined: Fri Sep 29, 2017 7:04 am

Re: Deriving these Equations

I believe it needs to explicitly show [A]o or else we are unsure what order concentration is given

Julie Steklof 1A
Posts: 50
Joined: Thu Jul 13, 2017 3:00 am

Re: Deriving these Equations

It would need to have the 0 subscript to be [A] initial.

Natalie LeRaybaud 1G
Posts: 54
Joined: Thu Jul 13, 2017 3:00 am

Re: Deriving these Equations

Yes I agree that it would have to be explicitly shown as [A]0 because otherwise it could be [A]t which refers to the final concentration at a certain time. So it is necessary to be able to differentiate between the 2.

204932558
Posts: 23
Joined: Fri Sep 29, 2017 7:05 am

Re: Deriving these Equations

[A}0 means the initial concentration. [A} is the concentration at any given time.

Michelle Lee 2E
Posts: 64
Joined: Thu Jul 27, 2017 3:01 am

Re: Deriving these Equations

Always try to refer to equations like the ones we used in class. You can solve for [A]0 but don't assume [A] is [A]0.
For plots specifically for first, second and zero order, the axes are always time by [A], not [A]0.

Ivy Lu 1C
Posts: 54
Joined: Thu Jul 27, 2017 3:00 am

Re: Deriving these Equations

Unless it's given [A]0 then [A] is just the concentration at the given time, not the initial concentration.

Tia Tomescu 2D
Posts: 42
Joined: Fri Sep 29, 2017 7:06 am

Re: Deriving these Equations

[A] is concentration (at any time), and [A]0 is concentration at t=0.