1)
The activation energy of a certain reaction is 35.3 kJ/mol. At 20 degrees C, the rate constant is 0.0130 s^-1. At what temperature would this reaction go twice as fast?
Answer in units of degrees Celsius.
i think the answer is around 34, but i keep in getting it screwed up.
2)
Consider the following multistep reaction:
C + D <> CD (fast)
CD + D > CD2 (slow)
CD2 + D > CD3 (fast)
C + 3D > CD3 (overall)
determine the rate law for the overall reaction
Answer should be in k[A][B]^2 format
I know the overall reaction has much to do with the slow reaction, but i don't get how to incorporate that into its proper format based on its order
3)
The reactant concentration in a zero-order reaction was 0.100 M after 125 s and 1.50×10−2 M after 385 s. What is the rate constant for this reaction?
What was the initial reactant concentration for the reaction?
I found the rate constant to be 3.27 x 10^-4 M/s, but im having trouble finding initial reactant concentration...
an equation that mite help..
[A]= - kt + [A]0
[A]0 is the initial reactant rate i beleieve.. i thinks...
1)
The activation energy of a certain reaction is 35.3 kJ/mol. At 20 degrees C, the rate constant is 0.0130 s^-1. At what temperature would this reaction go twice as fast?
Answer in units of degrees Celsius.
i think the answer is around 34, but i keep in getting it screwed up.
How are you solving it? Post your work and I'll try to find the error. You should be using the Arrhenius equation.
Also, make sure activation energy is J/mol. Also make sure you are using temperature in Kelvin.
3)
The reactant concentration in a zero-order reaction was 0.100 M after 125 s and 1.50×10−2 M after 385 s. What is the rate constant for this reaction?
What was the initial reactant concentration for the reaction?
I found the rate constant to be 3.27 x 10^-4 M/s, but im having trouble finding initial reactant concentration...
an equation that mite help..
[A]= - kt + [A]0
[A]0 is the initial reactant rate i beleieve.. i thinks...
Can't you simply take the initial equation you had, which is,
[A] = [A]o - kt (that's how you found k is it not?), then
substitute A = 0.1 and substitute your value of k, and 125 for t, then solve for [A]o? You could also use 1.5 x 10^-2 for (A) and 385 for t and your value of k and get the same value although I didn't try it. Check my thinking. I found about 0.14 M or so using the first suggetion above.
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1) To find the temperature at which the reaction goes twice as fast, we can use the Arrhenius equation:
k1 = A1 * e^(-Ea1/RT1)
k2 = A2 * e^(-Ea2/RT2)
Where k1 and k2 are the rate constants at temperatures T1 and T2, Ea1 and Ea2 are the activation energies, R is the gas constant (8.314 J/mol * K), and A1 and A2 are the pre-exponential factors.
Rearranging the equation, we can solve for T2:
T2 = (Ea2 - (Ea1 * ln(k2/k1))) / (R * ln(k2/k1))
To find the temperature at which the reaction goes twice as fast, we need to find T2 when k2 = 2 * k1.
Plugging in the values from the question:
Ea1 = 35.3 kJ/mol
T1 = 20 degrees Celsius = 293 K
k1 = 0.0130 s^-1
k2 = 2 * k1 = 0.0260 s^-1
Using the equation above, calculate T2. Converting the answer from Kelvin to degrees Celsius will give you the final answer.
2) To determine the rate law for the overall reaction, we need to look at the slowest step in the reaction mechanism, which is CD + D > CD2.
The rate law for this step can be determined by looking at the stoichiometric coefficients of the reactants: CD and D. The rate equation for this step is:
rate = k * [CD] * [D]
Since this is the rate-determining step, the rate law for the overall reaction will be the same as the rate law for this step:
rate = k * [CD] * [D]
The overall rate law is in the form k[A]^x[B]^y, but in this case, the reactants are CD and D, not A and B.
Therefore, the rate law for the overall reaction is k[CD][D]^2.
3) In a zero-order reaction, the concentration of the reactant does not affect the rate of the reaction. Therefore, the rate of the reaction remains constant throughout.
The rate constant (k) can be calculated using the equation:
k = (Change in concentration of reactant) / (Change in time)
From the given information, we can determine the change in concentration and time as:
Change in concentration = [A]0 - [A]
Change in time = t - t0
Substituting these values into the equation for the rate constant, we get:
k = ([A]0 - [A]) / (t - t0)
Using the provided values:
[A]0 = initial concentration of reactant
[A] = concentration of reactant after a certain time
t0 = initial time
t = time after which the concentration is measured
You have already calculated the rate constant, so you can rearrange the equation to solve for [A]0:
[A]0 = [A] + k(t - t0)
Substituting the values you have, you can solve for [A]0.