I WILL AWARD all points if anyone can guide me on this.... I am doing kinetics b

Question

I WILL AWARD all points if anyone can guide me on this....

I am doing kinetics by colorimetry.....

So far I have found the slope vs time, I have found it is in the first order..So please, help me.

I am trying to figure out what to do next....concentration initial of CV is .00003 M and the OH is negligible. I am trying to find the kobs.

How do i do this, I dont understand what I plug in. Next---- Six trials were done..... at different temps.... I am wondering how to find kobs... what to plug in.... please help me

Explanation / Answer

for 1st order reaction the governing equations are

1) r = K*[A] r= rate K = rate constant [A] concentration of reactant

2) Kt = ln[A0] - ln[A] [A0] = initial conc

so from 2nd equation we find that curve b/w ln[A] and t will be linear with slope = -K and intercept = ln[A0]

now in your ques tou know the value of [Ao] = 0.0003M

also tou have found the curve so

to find Kobs use equation 2

taking any value of [A] from your curve and corresponding t also

now ata different temperatures the value of Kobs will change

this can be found using the equation

Kobs = Ko*e^(-Ea/RT) Ko is constant for all temp Ea is activation energy

in other form

K1/K2 = Ea/R(1/T2 - 1/T1)

if you know the value of Kobs at any two temp you will get the value of Ea then from the previous eq you get the value of Ko

after this tou can find the value of Kobs at ant temp you want

Hope this helps :)

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