[candidateof]

Hello,

I am having a hard time solving this question about the TST:

If the following gas-phase radical recombination reaction

.CH₃+.CH₃ C₂H₆

has a rate constant of 0.22 L mole^-1 min^-1 at 600^oC. According to transition state theory, the reaction's rate at 900^oC is:

a) 0.22 L mole^-1 min^-1
b) 0.37 L mole^-1 min^-1
c) 0.33 L mole^-1 min^-1
d) 0.30 L mole^-1 min^-1
e) 0.44 L mole^-1 min^-1

---------------------------------

I thought of using the equation:
k=(k_BT/h)e^G/RT
for the first T and get delta G at transition state, and then calculate the second k at 900 using the same G. But I think it is wrong since the G is changing with changing the temperature, right?

Regards,

[Schrödinger]

Hint 1 : Use the Arrhenius equation.
Hint 2 : What is the activation energy for reactions in which free radicals combine?

[candidateof]

Hint 1 : Use the Arrhenius equation.
Hint 2 : What is the activation energy for reactions in which free radicals combine?

Dear Schrödinger,

Thank you for your helpful hints. Since the activation energy here is very small, we assume it is zero. Now, using the Arrhenius equation, the preexponential factor equal to k(E_a is zero). Taking the ratio of the two Arrhenius equations at different temperatures. we get:

ln(k₁/k₂)=E(-1/(RT₁)+1/(RT₂)) (since E=0)

  (k₁/k₂)=1
  k₁=k₂

But it is not correct, there must be somethin I am missing, right?

[Schrödinger]

The answer is not a) ? Well I'll be damned Which of the options is correct according to the book?

[candidateof]

The answer is not a) ? Well I'll be damned Which of the options is correct according to the book?

LOL I don't have the right answer actually, but I have chosen this answer by chance in my quiz, and got zero  .

So this is your suggestion of solving this question, or I did not get you yet?

Thanks for sharing your information  ..

[candidateof]

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