Calculating k

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Calculating k

Postby juleschang16 » Mon Mar 11, 2019 10:20 pm

I understand how to find m and n using concentrations of different initial rates but then how do you find k? Do you just plug in a random rate with its corresponding concentrations?

caseygilles 1E
Posts: 73
Joined: Fri Sep 28, 2018 12:18 am

Re: Calculating k

Postby caseygilles 1E » Mon Mar 11, 2019 10:34 pm

Yes, if you are given initial concentrations for every substance in the rate law and you are given the rate, we can use simple math to find k.
Example: for A+B---> products, rate=1.5 * 10^-7 mol/L*s and [A]=2.0 * 10^-2 mol/L , [B]=3.7 * 10^-2 mol/L:
rate=k[A][B] ------- k=rate/[A][B]-------- k= (1.5 * 10^-7 mol/L*s )/((2.0 * 10^-2 mol/L) * (3.7 * 10^-2 mol/L)) = 2.03 * 10^-4

Adam Vuilleumier 2K
Posts: 60
Joined: Fri Sep 28, 2018 12:27 am

Re: Calculating k

Postby Adam Vuilleumier 2K » Mon Mar 11, 2019 10:53 pm

Since you know concentrations, unique rate (from table), m and n (from prior calculations), you only have one unknown variable (k). Therefore, by plugging in all these values, you'll be able to get k.

Brian Chang 2H
Posts: 65
Joined: Fri Sep 28, 2018 12:17 am

Re: Calculating k

Postby Brian Chang 2H » Wed Mar 13, 2019 12:36 pm

If you have m and n you can plug them in to find K,

similarly, you can use k to derive either m or n.

You CANNOT solve for more than 1 unknown though.

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