Question 1

Which of the following is a rate law for a reaction that is first order with respect to oxygen?

Accepted Answer

The rate law for a reaction that is first order with respect to oxygen should have the concentration of O2 raised to the power of 1. In option E, [O2] is raised to the power of 1, indicating first order with respect to oxygen.

Question 2

The first-order decay of radon has a half-life of 3.823 days.How many grams of radon decomposes after 5.55 days if the sample initially weighs 100.0 grams?

Accepted Answer

The answer of The first-order decay of radon has a...

Question 3

The first-order rearrangement of CH₃NC is measured to have a rate constant of 3.61 × 10^-15 s^-1 at 298 K and a rate constant of 8.66 × 10^-7 s^-1 at 425 K.Determine the activation energy for this reaction.

Accepted Answer

The answer of The first-order rearrangement of CH₃NC is measured...

Question 4

Derive an expression for a "1/4-life" for a first-order reaction.

Accepted Answer

The answer of Derive an expression for a "1/4-life" for...

Question 5

A reaction has a rate constant of 6.0 × 10^-3 L² mol^-2 s^-1 at 10°C.If its activation energy is 84 kJ/mol,what is the value of the rate constant at 50°C?

Accepted Answer

The answer of A reaction has a rate constant of...

Question 6

A reaction occurs via the following sequence of elementary steps.What is the rate law based on this reaction mechanism? 1^st step: A + B → 2C + D slow 2^nd step: C → E fast 3^rd step: D → 2F fast

Accepted Answer

The rate-determining step is the first step, which is slow. The rate law is based on the reactants in the rate-determining step, which are A and B. Therefore, the rate law is rate = k[A][B].

Question 7

Identify the rate-determining step.

Accepted Answer

The rate-determining step is the slowest step in a reaction, as it limits the overall rate of the reaction.

Question 8

If the activation energy for a given compound is found to be 42.0 kJ/mol,with a frequency factor of 8.0 × 10¹⁰ s^-1,what is the rate constant for this reaction at 298 K?

Accepted Answer

The rate constant can be calculated using the Arrhenius equation:

k = Ae^(-Ea/RT)

where k is the rate constant, A is the frequency factor, Ea is the activation energy, R is the gas constant (8.314 J/mol*K), and T is the temperature in Kelvin.

Plugging in the values given:

k = (8.0 × 10^13 s^-1) * e^(-42000 J/mol / (8.314 J/mol*K * 298 K))

k = 3.5 × 10^-13 s^-1

Therefore, the best choice is E.

Question 9

For a reaction,what generally happens if the temperature is increased?

Accepted Answer

Increasing the temperature of the reactants generally increases the rate of the reaction by increasing the number of collisions between the molecules and increasing the kinetic energy of the molecules. This results in an increase in the rate constant (k) and thus an increase in the reaction rate.

Question 10

Given the following proposed mechanism,predict the rate law for the overall reaction. A₂ + 2B → 2AB (overall reaction) Mechanism A₂ ⇌ 2A fast A + B → AB slow

Accepted Answer

The answer of Given the following proposed mechanism,predict the rate...

Question 11

Which of the following statements is TRUE?

Accepted Answer

The rate constant is dependent on temperature, as the reaction rate increases with an increase in temperature. Choice A is false as the activation energy does affect the rate constant. Choice B is false as a catalyst lowers the activation energy. Choice D is false as a homogeneous catalyst can lower the activation energy of a reaction. Therefore, the only true statement is C.

Question 12

The first-order decay of radon has a half-life of 3.823 days.How many grams of radon remain after 7.22 days if the sample initially weighs 250.0 grams?

Accepted Answer

The answer of The first-order decay of radon has a...

Question 13

A reaction is found to have an activation energy of 38.0 kJ/mol.If the rate constant for this reaction is 1.60 × 10² M^-1s^-1 at 249 K,what is the rate constant at 436 K?

Accepted Answer

We can use the Arrhenius equation to solve for the new rate constant at 436 K:

k₂ = A * exp(-Ea/RT₂)

where k₂ is the new rate constant, A is the pre-exponential factor (given as 1.60 × 10^12 s^-1), Ea is the activation energy (given as 38.0 kJ/mol), R is the gas constant (8.31 J/mol*K), and T₂ is the new temperature in Kelvin (given as 436 K).

Plugging in the values and solving, we get:

k₂ = (1.60 × 10^12 s^-1) * exp(-38.0 kJ/mol / (8.31 J/mol*K * 436 K))
    = 4.20 × 10^15 s^-1

Therefore, the best choice is (D) 4.20 × 10^15 s^-1.

Question 14

If the activation energy for a given compound is found to be 103 kJ/mol,with a frequency factor of 4.0 × 10¹³ s^-1,what is the rate constant for this reaction at 398 K?

Accepted Answer

The rate constant (k) can be calculated using the Arrhenius equation: $k = A \exp\left(-\frac{E_a}{RT}\right)$, where $A$ is the frequency factor, $E_a$ is the activation energy in J/mol (103 kJ/mol = 103,000 J/mol), $R$ is the gas constant (8.314 J/mol·K), and $T$ is the temperature in Kelvin (398 K). Plugging in the values: $k = 4.0 \times 10^{13} \exp\left(-\frac{103,000}{8.314 \times 398}\right)$, which calculates to approximately 1.2 s^-1, making option A correct.

Question 15

A reaction occurs via the following sequence of elementary steps.What is the reaction intermediate? 1^st step: A + 2B → 2C 2^nd step: 2C → D

Accepted Answer

The reaction intermediate is the species that is formed in one step and consumed in a later step. In this case, C is formed in the first step and then consumed in the second step to form D. Therefore, C is the reaction intermediate.

Question 16

A reaction is found to have an activation energy of 108 kJ/mol.If the rate constant for this reaction is 4.60 × 10^-6 s^-1 at 275 K,what is the rate constant at 366 K?

Accepted Answer

The answer of A reaction is found to have an...

Question 17

A reaction is followed and found to have a rate constant of 3.36 × 10⁴ M^-1s^-1 at 344 K and a rate constant of 7.69 M^-1s^-1 at 219 K.Determine the activation energy for this reaction.

Accepted Answer

The Arrhenius equation relates the rate constant, k, to temperature, T, and activation energy, Ea:

k = Ae^(-Ea/RT)

where A is the pre-exponential factor and R is the gas constant.

Taking the natural logarithm of this equation gives:

ln(k) = ln(A) - (Ea/RT)

We can use this equation to determine the activation energy by using the rate constants at two different temperatures and solving for Ea. Let's use the data given at 344 K and 219 K.

For 344 K:
k1 = 3.36 × 10^14 s^-1
T1 = 344 K

For 219 K:
k2 = 7.69 × 10^1 s^-1
T2 = 219 K

Taking the ratio of the two equations gives:

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

Solving for Ea:

Ea/R = (ln(k1/k2))/[(1/T2)-(1/T1)]
Ea/R = (ln(3.36 × 10^14/7.69 × 10^1))/[(1/219)-(1/344)]
Ea/R = 49.8
Ea = (R)(49.8)
Ea = (8.314 J/mol-K)(49.8)
Ea = 414.8 J/mol

Converting J/mol to kJ/mol:

Ea = 0.4148 kJ/mol

Therefore, the answer is B) 42.0 kJ/mol (rounded to one significant figure).

Question 18

The second-order decomposition of NO₂ has a rate constant of 0.255 M^-1s^-1.How much NO₂ decomposes in 4.00 s if the initial concentration of NO₂ (1.00 L volume)is 1.33 M?

Accepted Answer

The second-order rate law for the decomposition of NO₂ is given as: rate = k[NO₂]^2 where k is the rate constant. We are given that k = 0.255 M^-1s^-1. We need to find the amount of NO₂ that decomposes in 4.00 s when the initial concentration is 1.33 M. We can use the integrated rate law for a second-order reaction to solve this problem: 1/[NO₂] - 1/[NO₂]o = kt where [NO₂]o is the initial concentration, t is the time elapsed, and [NO₂] is the concentration at time t. Substituting the given values in the above equation, we get: 1/[NO₂] - 1/1.33 = (0.255 M^-1s^-1) * (4.00 s) Solving for [NO₂], we get: [NO₂] = 0.77 M Thus, the amount of NO₂ that decomposes in 4.00 s is: (1.33 M - 0.77 M) * 1.00 L = 0.56 mol Therefore, the correct answer is D) 0.77 mol.

Question 19

Derive an expression for a "1/3-life" for a first-order reaction.

Accepted Answer

The answer of Derive an expression for a "1/3-life" for...

Question 20

The first-order decomposition of N₂O₅ at 328 K has a rate constant of 1.70 × 10^-3 s^-1.If the initial concentration of N₂O₅ is 2.88 M,what is the concentration of N₂O₅ after 12.5 minutes?

Accepted Answer

The concentration after a given time in a first-order reaction is calculated using the formula $[A]_t = [A]_0 e^{-kt}$, where $[A]_t$ is the concentration at time $t$, $[A]_0$ is the initial concentration, $k$ is the rate constant, and $t$ is the time in seconds. Given $k = 1.70 \times 10^{-3} \, \text{s}^{-1}$, $[A]_0 = 2.88 \, \text{M}$, and $t = 12.5 \, \text{minutes} = 750 \, \text{seconds}$, substituting these values into the formula gives a concentration of approximately $0.805 \, \text{M}$.

Quiz 15: Chemical Kinetics

Which of the following is a rate law for a reaction that is first order with respect to oxygen?

The first-order decay of radon has a half-life of 3.823 days.How many grams of radon decomposes after 5.55 days if the sample initially weighs 100.0 grams?

The first-order rearrangement of CH₃NC is measured to have a rate constant of 3.61 × 10^-15 s^-1 at 298 K and a rate constant of 8.66 × 10^-7 s^-1 at 425 K.Determine the activation energy for this reaction.

Derive an expression for a "1/4-life" for a first-order reaction.

A reaction has a rate constant of 6.0 × 10^-3 L² mol^-2 s^-1 at 10°C.If its activation energy is 84 kJ/mol,what is the value of the rate constant at 50°C?

A reaction occurs via the following sequence of elementary steps.What is the rate law based on this reaction mechanism? 1^st step: A + B → 2C + D slow 2^nd step: C → E fast 3^rd step: D → 2F fast

Identify the rate-determining step.

If the activation energy for a given compound is found to be 42.0 kJ/mol,with a frequency factor of 8.0 × 10¹⁰ s^-1,what is the rate constant for this reaction at 298 K?

For a reaction,what generally happens if the temperature is increased?

Given the following proposed mechanism,predict the rate law for the overall reaction. A₂ + 2B → 2AB (overall reaction) Mechanism A₂ ⇌ 2A fast A + B → AB slow

Which of the following statements is TRUE?

The first-order decay of radon has a half-life of 3.823 days.How many grams of radon remain after 7.22 days if the sample initially weighs 250.0 grams?

A reaction is found to have an activation energy of 38.0 kJ/mol.If the rate constant for this reaction is 1.60 × 10² M^-1s^-1 at 249 K,what is the rate constant at 436 K?

If the activation energy for a given compound is found to be 103 kJ/mol,with a frequency factor of 4.0 × 10¹³ s^-1,what is the rate constant for this reaction at 398 K?

A reaction occurs via the following sequence of elementary steps.What is the reaction intermediate? 1^st step: A + 2B → 2C 2^nd step: 2C → D

A reaction is found to have an activation energy of 108 kJ/mol.If the rate constant for this reaction is 4.60 × 10^-6 s^-1 at 275 K,what is the rate constant at 366 K?

A reaction is followed and found to have a rate constant of 3.36 × 10⁴ M^-1s^-1 at 344 K and a rate constant of 7.69 M^-1s^-1 at 219 K.Determine the activation energy for this reaction.

The second-order decomposition of NO₂ has a rate constant of 0.255 M^-1s^-1.How much NO₂ decomposes in 4.00 s if the initial concentration of NO₂ (1.00 L volume) is 1.33 M?

Derive an expression for a "1/3-life" for a first-order reaction.

The first-order decomposition of N₂O₅ at 328 K has a rate constant of 1.70 × 10^-3 s^-1.If the initial concentration of N₂O₅ is 2.88 M,what is the concentration of N₂O₅ after 12.5 minutes?

Quiz 15: Chemical Kinetics

Which of the following is a rate law for a reaction that is first order with respect to oxygen?

The first-order decay of radon has a half-life of 3.823 days.How many grams of radon decomposes after 5.55 days if the sample initially weighs 100.0 grams?

The first-order rearrangement of CH3NC is measured to have a rate constant of 3.61 × 10-15 s-1 at 298 K and a rate constant of 8.66 × 10-7 s-1 at 425 K.Determine the activation energy for this reaction.

Derive an expression for a "1/4-life" for a first-order reaction.

A reaction has a rate constant of 6.0 × 10-3 L2 mol-2 s-1 at 10°C.If its activation energy is 84 kJ/mol,what is the value of the rate constant at 50°C?

A reaction occurs via the following sequence of elementary steps.What is the rate law based on this reaction mechanism? 1st step: A + B → 2C + D slow 2nd step: C → E fast 3rd step: D → 2F fast

Identify the rate-determining step.

If the activation energy for a given compound is found to be 42.0 kJ/mol,with a frequency factor of 8.0 × 1010 s-1,what is the rate constant for this reaction at 298 K?

For a reaction,what generally happens if the temperature is increased?

Given the following proposed mechanism,predict the rate law for the overall reaction. A2 + 2B → 2AB (overall reaction) Mechanism A2 ⇌ 2A fast A + B → AB slow

Which of the following statements is TRUE?

The first-order decay of radon has a half-life of 3.823 days.How many grams of radon remain after 7.22 days if the sample initially weighs 250.0 grams?

A reaction is found to have an activation energy of 38.0 kJ/mol.If the rate constant for this reaction is 1.60 × 102 M-1s-1 at 249 K,what is the rate constant at 436 K?

If the activation energy for a given compound is found to be 103 kJ/mol,with a frequency factor of 4.0 × 1013 s-1,what is the rate constant for this reaction at 398 K?

A reaction occurs via the following sequence of elementary steps.What is the reaction intermediate? 1st step: A + 2B → 2C 2nd step: 2C → D

A reaction is found to have an activation energy of 108 kJ/mol.If the rate constant for this reaction is 4.60 × 10-6 s-1 at 275 K,what is the rate constant at 366 K?

A reaction is followed and found to have a rate constant of 3.36 × 104 M-1s-1 at 344 K and a rate constant of 7.69 M-1s-1 at 219 K.Determine the activation energy for this reaction.

The second-order decomposition of NO2 has a rate constant of 0.255 M-1s-1.How much NO2 decomposes in 4.00 s if the initial concentration of NO2 (1.00 L volume) is 1.33 M?

Derive an expression for a "1/3-life" for a first-order reaction.

The first-order decomposition of N2O5 at 328 K has a rate constant of 1.70 × 10-3 s-1.If the initial concentration of N2O5 is 2.88 M,what is the concentration of N2O5 after 12.5 minutes?

The first-order rearrangement of CH₃NC is measured to have a rate constant of 3.61 × 10^-15 s^-1 at 298 K and a rate constant of 8.66 × 10^-7 s^-1 at 425 K.Determine the activation energy for this reaction.

A reaction has a rate constant of 6.0 × 10^-3 L² mol^-2 s^-1 at 10°C.If its activation energy is 84 kJ/mol,what is the value of the rate constant at 50°C?

A reaction occurs via the following sequence of elementary steps.What is the rate law based on this reaction mechanism? 1^st step: A + B → 2C + D slow 2^nd step: C → E fast 3^rd step: D → 2F fast

If the activation energy for a given compound is found to be 42.0 kJ/mol,with a frequency factor of 8.0 × 10¹⁰ s^-1,what is the rate constant for this reaction at 298 K?

Given the following proposed mechanism,predict the rate law for the overall reaction. A₂ + 2B → 2AB (overall reaction) Mechanism A₂ ⇌ 2A fast A + B → AB slow

A reaction is found to have an activation energy of 38.0 kJ/mol.If the rate constant for this reaction is 1.60 × 10² M^-1s^-1 at 249 K,what is the rate constant at 436 K?

If the activation energy for a given compound is found to be 103 kJ/mol,with a frequency factor of 4.0 × 10¹³ s^-1,what is the rate constant for this reaction at 398 K?

A reaction occurs via the following sequence of elementary steps.What is the reaction intermediate? 1^st step: A + 2B → 2C 2^nd step: 2C → D

A reaction is found to have an activation energy of 108 kJ/mol.If the rate constant for this reaction is 4.60 × 10^-6 s^-1 at 275 K,what is the rate constant at 366 K?

A reaction is followed and found to have a rate constant of 3.36 × 10⁴ M^-1s^-1 at 344 K and a rate constant of 7.69 M^-1s^-1 at 219 K.Determine the activation energy for this reaction.

The second-order decomposition of NO₂ has a rate constant of 0.255 M^-1s^-1.How much NO₂ decomposes in 4.00 s if the initial concentration of NO₂ (1.00 L volume) is 1.33 M?

The first-order decomposition of N₂O₅ at 328 K has a rate constant of 1.70 × 10^-3 s^-1.If the initial concentration of N₂O₅ is 2.88 M,what is the concentration of N₂O₅ after 12.5 minutes?