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A certain first-order reaction has a rate constant of 2.65×10 2 s1 at 20 C. What

ID: 524237 • Letter: A

Question

A certain first-order reaction has a rate constant of 2.65×102 s1 at 20 C. What is the value of k at 58 C if Ea = 79.0 kJ/mol ?

A certain first-order reaction has a rate constant of 2.65×102 s1 at 20 C. What is the value of k at 58 C if Ea = 122 kJ/mol ?

Part A A certain first-order reaction has a rate constant of 2.65x10-2 s 1 at 20 o C. What is the value of k at 58 oC if Ea 79.0 kJ/mol Express your answer using two significant figures. Submit My Answers Give U Part B A certain first-order reaction has a rate constant of 2.65x10 2 s 1 at 20 oC. What is the value of k at 58 oC if Ea 122 kJ/mol Express your answer using two significant figures.

Explanation / Answer

A)
T1 = 20.0 oC =(20.0+273)K = 293.0 K
T2 = 58.0 oC =(58.0+273)K = 331.0 K
K1 = 0.0265 s-1
Ea = 79.0 KJ/mol = 79000.0 J/mol

use:
ln(K2/K1) = (Ea/R)*(1/T1 - 1/T2)
ln(K2/0.0265) = (79000.0/8.314)*(1/293.0 - 1/331.0)
ln(K2/0.0265) = 9502*(3.918*10^-4)
K2 = 1.097 s-1
Answer: 1.1 s-1

B)
T1 = 20.0 oC =(20.0+273)K = 293.0 K
T2 = 58.0 oC =(58.0+273)K = 331.0 K
K1 = 0.0265 s-1
Ea = 122.0 KJ/mol = 122000.0 J/mol

use:
ln(K2/K1) = (Ea/R)*(1/T1 - 1/T2)
ln(K2/0.0265) = (122000.0/8.314)*(1/293.0 - 1/331.0)
ln(K2/0.0265) = 14674*(3.918*10^-4)
K2 = 8.323 s-1
Answer: 8.3 s-1

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