The first-order isomerization reaction: cyclopropane → propene has a rate constant of 1.10×10-4 s-1 at 470°C and 5.70×10-4 s-1 at 500°C. What is the activation energy, Ea, for the reaction?

Respuesta :

Answer:

Activation energy, Ea, for the reaction 261.7 kj/mole

Explanation:

Given

Rate constant at 470 ⁰C (K₁) = 1.10 x 10⁻⁴ s⁻¹ and rate constant at 500⁰C (K₂) = 5.7 x 10⁻⁴ s⁻¹

Temperature (T₁) = 470 + 273 = 743 K and

temperature (T₂) = 500 + 273 = 773 K

Activation energy (Eₐ) = ?

Universal gas constant (R) = 8.314 J. K⁻¹. mole⁻¹

We know   log[tex]\frac{K_{2} }{K_{1} }[/tex] = [tex]\frac{E_{a} }{2.303XR}[/tex][tex]\frac{(T_{2}-T_{1} ) }{T_{2}T_{1} }[/tex]

              ⇒ log [tex]\frac{5.7 X 10^{-4} }{1.1 X 10^{-4} }[/tex] = [tex]\frac{E_{a} }{2.303X8.314}[/tex] [tex]\frac{(773 - 743)}{773X743}[/tex]

              ⇒ 0.714 = [tex]\frac{E_{a}X30 }{10996950.3}[/tex]

              ⇒ Eₐ = [tex]\frac{7851822.5}{30}[/tex] j/mole = 261.7 Kj/mole

The activation energy of the reaction is 1.37 * 10^5 J

What is activation energy?

The activation energy is the energy possessed by the particles of a body in order to be able to participate in chemical reaction.

Using the formula;

ln(k2/k1) = -Ea/R(1/T2 - 1/T1)

Substituting values, we have;

ln(5.70×10-4 /1.10×10-4) = -Ea/8.314(1/500 - 1/470)

1.65 = -Ea/8.314(0.0020 - 0.0021)

1.65 = 0.0001Ea/8.314

Ea = 1.65 * 8.314/0.0001

Ea = 1.37 * 10^5 J

The activation energy of the reaction is 1.37 * 10^5 J

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