Question

The rate constants for a first order reaction are found to be 2.76*10-5 s^-1 at 25 degrees celsius and 6.65*10^-4 s^-1 at 50 degrees celsius, respectively. A) Calculate the activation energy Ea in kilojoules per mole. B) Calculate the rate constant at 75 degrees celsius

Answer #1

a)

Given:

T1 = 25 oC

=(25+273)K

= 298 K

T2 = 50 oC

=(50+273)K

= 323 K

K1 = 2.76*10^-5 s-1

K2 = 6.65*10^-4 s-1

use:

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

ln(6.65*10^-4/2.76*10^-5) = ( Ea/8.314)*(1/298 - 1/323)

3.182 = (Ea/8.314)*(2.597*10^-4)

Ea = 101856 J/mol

Ea = 101.8556 KJ/mol

Answer: 101.9 KJ/mol

b)

Given:

T1 = 25 oC

=(25+273)K

= 298 K

T2 = 75 oC

=(75+273)K

= 348 K

K1 = 2.76*10^-5 s-1

Ea = 101.8556 KJ/mol

= 101856 J/mol

use:

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

ln(K2/2.76*10^-5) = (101856/8.314)*(1/298 - 1/348.0)

ln(K2/2.76*10^-5) = 12251*(4.821*10^-4)

K2 = 1.014*10^-2 s-1

Answer: 1.01*10^-2 s-1

Rate constants for the reaction A → B + C are 1.55 s-1 at 298 K
and 17.2 s-1 at 308 K.
A. What is the activation energy (Ea) for this reaction?
B. What would the rate constant be at 318 K?
C. What is the order of this reaction?

A reaction has a first order rate constant of 3.63x10-5 s-1 at
25 degrees and 0.00203 s-1 at 75 degrees. What is the value of the
rate constant at 53 degrees?

The rate constant of a first-order reaction is 3.20 × 10−4 s−1
at 350.°C. If the activation energy is 135 kJ/mol, calculate the
temperature at which its rate constant is 9.15 × 10−4 s−1.

A certain first-order reaction has a rate constant of
2.30×10−2 s−1 at 25 ∘C . What is the value of k
at 63 ∘C if Ea = 74.0 kJ/mol ?
Express your answer using two significant figures.
Part B
Another first-order reaction also has a rate constant of
2.30×10−2 s−1 at 25 ∘C . What is the value of k
at 63 ∘C if Ea = 128 kJ/mol ?
Express your answer using two significant figures.

Part A
A certain first-order reaction has a rate constant of
3.00×10−2 s−1 at 25 ∘C . What is the value of k
at 69 ∘C if Ea = 77.0 kJ/mol ?
Express your answer using two significant figures.
Part B
Another first-order reaction also has a rate constant of
3.00×10−2 s−1 at 25 ∘C . What is the value of k
at 69 ∘C if Ea = 115 kJ/mol ?
Express your answer using two significant figures.

at 25 degrees celsius, a rate constant has the value 5.21*10^-8
L /Mol*s. If the activation energy is 75.2 kj/mol, calculate the
rate constant when the temperature is 50 degrees celsius.

1) A first order reaction has an activation energy of 66.6
kJ/mol and a frequency factor (Arrhenius constant) of 8.78 x
1010 sec -1. Calculate the rate constant at
19 oC. Use 4 decimal places for your answer.
2) A first order reaction has a rate constant of 0.988 at 25
oC and 9.6 at 33 oC. Calculate the value of
the activation energy in KILOJOULES (enter answer to one decimal
place)

-(a) A certain first-order reaction has a rate
constant of 2.75 × 10–2 s–1 at 20 °C. What is
the value of k at 60 °C if Ea
= 75.5 kJ/mol?
(b) Another first-order reaction also has a
rate constant of 2.75 × 10–2 s–1 at 20 °C.
What is the value of k at 60 °C if
Ea = 125 kJ/mol?
(c) What assumptions do you need to make in
order to calculate answers for parts (a) and (b)?

If a first order reaction has a rate constant of 4.15 X
10-2 s-1 at a temperature of
24.5oC, what would the value of k be if the reaction
temperature was changed to 52oC given that the
activation energy is 67.8 kJ/mol?

the rate constant of a reaction is 4.0x10^-3 s^-1 at 25 degrees
C, and the activation energy is 33.6 kJ/mol. What is k at 75
degrees C? Enter in scientific notation

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