Rate constant calculation Using the Arrhenius equation

  • #1
Madelin Pierce
24
2

Homework Statement


A reaction has a rate constant of 0.0117/s at 400.0 K and 0.689/s at 450.0 K. What is the value of the rate constant (to 1 decimal place) at 538 K?

Homework Equations


ln k= ln A-E[a]/RT

The Attempt at a Solution


I'm not sure how to approach this problem, although I know the arrhenius equation is involved. When I submitted it blank on the computer, the computer hinted at finding enthalpy. But I don't know how. [/B]
 

Answers and Replies

  • #2
Wrichik Basu
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$$\ln{k_1} = \ln{A} - \frac{E_a}{RT_1} \text{...Eqn. 1}$$ and $$\ln{k_2} = \ln{A} - \frac{E_a}{RT_2} \text{...Eqn. 2}$$ for two different ##k_1## and ##k_2## at two different temperatures ##T_1## and ##T_2##.

Subtract Eqn1 from Eqn2:$$\ln{\frac{k2}{k1}} = - E_a R \left(\frac{1}{T_1} - \frac{1}{T_2}\right) \text{...Eqn. 3}$$ Find ##E_a## by putting in the appropriate values.

Then put ##E_a## in Eqn1 or Eqn2, and find ##A##.

Then use $$\ln{k} = \ln{A} - \frac{E_a}{RT}$$ and put ##T= 538K## and find ##k##, the rate constant at temperature ##T##. You already have ##E_a## and ##A##, and they remain constant.
 

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