Question 1

The half life for a first order reaction is 45 min. What is the rate constant in units of s^-1

Accepted Answer

The half-life for a first-order reaction is given by the equation: t1/2 = ln(2)/k, where k is the rate constant.
Plugging in the given half-life of 45 min:
45 min = ln(2)/k
Rearranging to solve for k:
k = ln(2)/45 min = 2.6 x 10^-4 s^-1
Therefore, the rate constant in units of s^-1 is 2.6 x 10^-4 s^-1. Since none of the answer choices match this unit, we need to convert to the units given in the answer choices. 
Multiplying by 60 s/min, we get:
k = 0.0156 s^-1
The answer choice closest to this value is (A) 0.015 s^-1, but it is slightly lower. The true answer is actually closer to (B) 65 s^-1, but still not an exact match. Answer choice (C) 2.6 x 10^-4 s^-1 is the only one that matches the given units, and is the correct choice.

Question 2

A reaction was experimentally determined to follow the rate law, Rate = k[A]² where k = 0.456 s^-1M^-1. Starting with [A]_o = 0.500 M, how many seconds will it take for [A]_t = 0.250 M

Accepted Answer

For a second-order reaction, the integrated rate law is 1/[A]_t = kt + 1/[A]_o. Plugging in the values: 1/0.250 = 0.456 * t + 1/0.500. Solving for t gives t = 4.39 s.

Question 3

The following initial rate data apply to the reaction below.F₂(g) + 2Cl₂O(g) $\rarr$2FClO₂(g) + Cl₂(g) $\begin{array}{lccc} \mathrm{Expt.\#} & \left[\mathrm{F}_{2}\right](\mathrm{M}) & \left[\mathrm{Cl}_{2} \mathrm{O}\right](\mathrm{M}) & \mathrm{Initial~ rate} (\mathrm{M} / \mathrm{s}) \\hline 1 & 0.05 & 0.010 & 5.0 \times 10^{-4} \ 2 & 0.05 & 0.040 & 2.0 \times 10^{-3} \ 3 & 0.10 & 0.010 & 1.0 \times 10^{-3} \ \end{array}$ Which of the following is the rate law (rate equation) for this reaction

Accepted Answer

The reaction rate only depends on the concentrations of the reactants F₂ and Cl₂O, which are both raised to the first power. Therefore, the rate law is rate = k[F₂][Cl₂O], which is choice C. The other answer choices involve additional powers or additional reactants, which do not match the given initial rate data.

Question 4

A reaction was experimentally determined to follow the rate law, Rate = k[A] where k = 0.15 s^-1. Starting with [A]_o = 0.225M, how many seconds will it take for [A]_t = 0.0350M

Accepted Answer

Given the rate law is first order, we can use the first-order kinetics equation: $t = \frac{1}{k} \ln \left(\frac{[A]_0}{[A]_t}\right)$. Substituting $k = 0.15 \, \text{s}^{-1}$, $[A]_0 = 0.225 \, \text{M}$, and $[A]_t = 0.0350 \, \text{M}$, we find $t \approx 12 \, \text{s}$.

Question 5

The isomerization of cyclopropane to form propene is a first-order reaction.  At 760 K, 15% of a sample of cyclopropane changes to propene in 6.8 min. What is the half-life of cyclopropane at 760 K

Accepted Answer

The answer of The isomerization of cyclopropane to form propene...

Question 6

At 700 K, the rate constant for the following reaction is 6.2 * 10^-4 min^-1. How many minutes are required for 20% of a sample of cyclopropane to isomerize to propene

Accepted Answer

The answer of At 700 K, the rate constant for...

Question 7

A certain reaction, reaction A$\rarr$ products, is first order with respect toA. Starting with [A] = 0.250M, it takes 45 min to reduce the concentration of A to 0.110M. What is its rate constant for this reaction

Accepted Answer

The answer of A certain reaction, reaction A$\rarr$ products, is...

Question 8

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. For the water to be safe for drinking, the concentration of this toxin must be below 1.5 x 10^-3 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day^-1. How long will it take for the water to be safe to drink

Accepted Answer

To solve this problem, we can use the first-order rate law:

ln ([toxin]t/[toxin]0) = -kt

where [toxin]t is the concentration of toxin at time t, [toxin]0 is the initial concentration of toxin, k is the rate constant, and t is time.

We can rearrange this equation to solve for t:

t = (ln ([toxin]0/[toxin]t))/k

Plugging in the given values, we get:

t = (ln (1.5 x 10^-3/0.63))/0.27 = 22 days (rounded to the nearest whole day)

Therefore, it will take 22 days for the water to be safe to drink. So the correct answer is D.

Question 9

The half life for a first order reaction is 27 min. How long will it take for 4 half lives to occur

Accepted Answer

For a first-order reaction, the time it takes for a certain number of half-lives to occur is simply the half-life multiplied by the number of half-lives. Therefore, for 4 half-lives, it would take 27 min/half-life * 4 half-lives = 108 min.

Question 10

Ammonium ion (NH₄⁺) reacts with nitrite ion (NO₂^-) to yield nitrogen gas and liquid water. The following initial rates of reaction have been measured for the given reactant concentrations. $\begin{array}{lccc} \text { Expt. \# } & {\left[\mathrm{NH}_{4}{ }^{+}\right]} & {\left[\mathrm{NO}_{2}{ }^{-}\right]} & \text {Initial rate }(\mathrm{M} / \mathrm{hr}) \ \hline 1 & 0.010 & 0.020 & 0.020 \ 2 & 0.015 & 0.020 & 0.030 \ 3 & 0.030 & 0.010 & 0.015 \end{array}$ Which of the following is the rate law (rate equation) for this reaction

Accepted Answer

The answer of Ammonium ion (NH₄⁺) reacts with nitrite ion...

Question 11

The isomerization of cyclopropane to propene follows first-order kinetics. At 700 K, the rate constant for this reaction is 6.2 * 10^-4 min^-1. How many minutes are required for 10.0% of a sample of cyclopropane to isomerize to propene

Accepted Answer

The answer of The isomerization of cyclopropane to propene follows...

Question 12

Appropriate units for a second-order rate constant are

Accepted Answer

The second-order rate constant is defined as k = k[M][N]/([M] + [N]) where [M] and [N] are the concentrations of the reactants. The units of k depend on the units of [M] and [N]. Since the order of the rate law is 2, the units of [M] and [N] are both M (molarity). Therefore, the units of k are 1/M·s, which is choice B.

Question 13

The data below were determined for the reaction shown below.S₂O₈^2- + 3I ^- (aq) $\rarr$2SO₄^2- + I₃^- $\begin{array}{lccc} \text { Expt. \# } & \left[\mathrm{S}_{2-} \mathrm{O}_{8}{ }^{2}\right] & {[I-]} & \text { Initial Rate } \ \hline 1 & 0.038 & 0.060 & 1.4 \times 10^{-5} \mathrm{M} / \mathrm{s} \ 2 & 0.076 & 0.060 & 2.8 \times 10^{-5} \mathrm{M} / \mathrm{s} \ 3 & 0.076 & 0.030 & 1.4 \times 10^{-5} \mathrm{M} / \mathrm{s} \end{array}$ The rate law for this reaction must be:

Accepted Answer

The rate law for this reaction has a stoichiometric coefficient of 1 for both reactants, which indicates a simple first-order reaction. Therefore, the rate law must have the form rate = k[A][B], where A is the concentration of S₂O₈^2- and B is the concentration of I ^-. Option E is the only one that matches this form.

Question 14

Benzoyl chloride, C₆H₅COCl, reacts with water to form benzoic acid, C₆H₅COOH, and hydrochloric acid. This first-order reaction is 25% complete after 26 s. How much longer would one have to wait in order to obtain 99% conversion of benzoyl chloride to benzoic acid

Accepted Answer

The reaction is first-order, so we use the first-order kinetics formula. Given that 25% completion takes 26 s, we can calculate the rate constant (k) and then use it to find the time for 99% completion. The additional time required is approximately 393 s.

Question 15

Nitric oxide reacts with chlorine to form nitrosyl chloride, NOCl. Use the following data to determine the rate equation for the reaction.NO + ¹/₂Cl₂$\rarr$ NOCl $\begin{array}{llll} \text { Expt. \# } & [\mathrm{NO}] & {\left[\mathrm{Cl}_{2}\right]} & {\text { Initial Rate }} \ \hline 1 & 0.22 & 0.065 & 0.96 \mathrm{M} / \mathrm{min} \ 2 & 0.66 & 0.065 & 8.6 \mathrm{M} / \mathrm{min} \ 3 & 0.44 & 0.032 & 1.9 \mathrm{M} / \mathrm{min} \end{array}$

Accepted Answer

The answer of Nitric oxide reacts with chlorine to form...

Question 16

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day^-1. How long will it take for half of the toxin to decompose

Accepted Answer

The answer of A city's water supply is contaminated with...

Question 17

The isomerization of cyclopropane to form propene is a first-order reaction.  At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min. Determine the rate constant for this reaction at 760 K.

Accepted Answer

The reaction follows first-order kinetics, therefore its rate can be described by the following equation:
ln[N(t)/N0] = -kt
where N(t) is the concentration at time t, N0 is the initial concentration of cyclopropane, k is the rate constant, and t is time. We know that 85% of cyclopropane changes into propene in 79.0 min, therefore the concentration ratio is N(t)/N0 = 0.15. Substituting the values into the equation, we get:
ln(0.15) = -k(79.0 min)
k = -ln(0.15)/79.0 min ≈ 2.40 × 10^-2 min^-1 ≈ 2.40 × 10^10 s^-1. 
Thus, the best choice is E.

Question 18

The first-order decomposition, A $\rarr$ products, has a rate constant of 0.150 s^-1. Starting with [A]_o = 0.350 M, how much time is required for [A]_t = 0.125 M

Accepted Answer

Explanation:The integrated rate law for a first-order reaction is:ln([A]t/[A]o) = -ktwhere [A]t is the concentration of A at time t, [A]o is the initial concentration of A, k is the rate constant, and t is time.We can use this equation to solve for t:t = -ln([A]t/[A]o)/kPlugging in the given values, we get:t = -ln(0.125/0.350)/0.150 s^-1 = 6.86 sTherefore, the correct answer is A.

Question 19

At 25^$\circ$C the rate constant for the first-order decomposition of a pesticide solution is 6.40 *10^-3 min^-1. If the starting concentration of pesticide is 0.0314 M, what concentration will remain after 62.0 min at 25^$\circ$C

Accepted Answer

For a first-order reaction, the concentration of the reactant at any time, $t$, can be 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. Given $k = 6.40 \times 10^{-3} \text{ min}^{-1}$, $[A]_0 = 0.0314 \text{ M}$, and $t = 62.0 \text{ min}$, substituting these values into the formula gives $[A]_t = 0.0314 \text{ M} \times e^{-(6.40 \times 10^{-3} \text{ min}^{-1})(62.0 \text{ min})}$, which calculates to approximately $2.11 \times 10^{-2} \text{ M}$, matching choice D.

Question 20

A certain first-order reaction A $\rarr$ B is 25% complete in 42 min at 25^$\circ$C. What is the half-life of the reaction

Accepted Answer

The answer of A certain first-order reaction A $\rarr$ B...

Quiz 13: Chemical Kinetics

The half life for a first order reaction is 45 min. What is the rate constant in units of s^-1

A reaction was experimentally determined to follow the rate law, Rate = k[A]² where k = 0.456 s^-1M^-1. Starting with [A]_o = 0.500 M, how many seconds will it take for [A]_t = 0.250 M

A reaction was experimentally determined to follow the rate law, Rate = k[A] where k = 0.15 s^-1. Starting with [A]_o = 0.225M, how many seconds will it take for [A]_t = 0.0350M

The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 15% of a sample of cyclopropane changes to propene in 6.8 min. What is the half-life of cyclopropane at 760 K

At 700 K, the rate constant for the following reaction is 6.2 * 10^-4 min^-1. How many minutes are required for 20% of a sample of cyclopropane to isomerize to propene

A certain reaction, reaction A $\rarr$ products, is first order with respect toA. Starting with [A] = 0.250M, it takes 45 min to reduce the concentration of A to 0.110M. What is its rate constant for this reaction

The half life for a first order reaction is 27 min. How long will it take for 4 half lives to occur

The isomerization of cyclopropane to propene follows first-order kinetics. At 700 K, the rate constant for this reaction is 6.2 * 10^-4 min^-1. How many minutes are required for 10.0% of a sample of cyclopropane to isomerize to propene

Appropriate units for a second-order rate constant are

Benzoyl chloride, C₆H₅COCl, reacts with water to form benzoic acid, C₆H₅COOH, and hydrochloric acid. This first-order reaction is 25% complete after 26 s. How much longer would one have to wait in order to obtain 99% conversion of benzoyl chloride to benzoic acid

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day^-1. How long will it take for half of the toxin to decompose

The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min. Determine the rate constant for this reaction at 760 K.

The first-order decomposition, A $\rarr$ products, has a rate constant of 0.150 s^-1. Starting with [A]_o = 0.350 M, how much time is required for [A]_t = 0.125 M

At 25^$\circ$C the rate constant for the first-order decomposition of a pesticide solution is 6.40 *10^-3 min^-1. If the starting concentration of pesticide is 0.0314 M, what concentration will remain after 62.0 min at 25^$\circ$C

A certain first-order reaction A $\rarr$ B is 25% complete in 42 min at 25^$\circ$C. What is the half-life of the reaction

Quiz 13: Chemical Kinetics

The half life for a first order reaction is 45 min. What is the rate constant in units of s-1

A reaction was experimentally determined to follow the rate law, Rate = k[A]2 where k = 0.456 s-1M-1. Starting with [A]o = 0.500 M, how many seconds will it take for [A]t = 0.250 M

A reaction was experimentally determined to follow the rate law, Rate = k[A] where k = 0.15 s-1. Starting with [A]o = 0.225M, how many seconds will it take for [A]t = 0.0350M

The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 15% of a sample of cyclopropane changes to propene in 6.8 min. What is the half-life of cyclopropane at 760 K

At 700 K, the rate constant for the following reaction is 6.2 * 10-4 min-1. How many minutes are required for 20% of a sample of cyclopropane to isomerize to propene

A certain reaction, reaction A →\rarr→ products, is first order with respect toA. Starting with [A] = 0.250M, it takes 45 min to reduce the concentration of A to 0.110M. What is its rate constant for this reaction

The half life for a first order reaction is 27 min. How long will it take for 4 half lives to occur

The isomerization of cyclopropane to propene follows first-order kinetics. At 700 K, the rate constant for this reaction is 6.2 * 10-4 min-1. How many minutes are required for 10.0% of a sample of cyclopropane to isomerize to propene

Appropriate units for a second-order rate constant are

Benzoyl chloride, C6H5COCl, reacts with water to form benzoic acid, C6H5COOH, and hydrochloric acid. This first-order reaction is 25% complete after 26 s. How much longer would one have to wait in order to obtain 99% conversion of benzoyl chloride to benzoic acid

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day-1. How long will it take for half of the toxin to decompose

The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min. Determine the rate constant for this reaction at 760 K.

The first-order decomposition, A →\rarr→ products, has a rate constant of 0.150 s-1. Starting with [A]o = 0.350 M, how much time is required for [A]t = 0.125 M

At 25 ∘\circ∘ C the rate constant for the first-order decomposition of a pesticide solution is 6.40 *10-3 min-1. If the starting concentration of pesticide is 0.0314 M, what concentration will remain after 62.0 min at 25 ∘\circ∘ C

A certain first-order reaction A →\rarr→ B is 25% complete in 42 min at 25 ∘\circ∘ C. What is the half-life of the reaction

The half life for a first order reaction is 45 min. What is the rate constant in units of s^-1

A reaction was experimentally determined to follow the rate law, Rate = k[A]² where k = 0.456 s^-1M^-1. Starting with [A]_o = 0.500 M, how many seconds will it take for [A]_t = 0.250 M

A reaction was experimentally determined to follow the rate law, Rate = k[A] where k = 0.15 s^-1. Starting with [A]_o = 0.225M, how many seconds will it take for [A]_t = 0.0350M

At 700 K, the rate constant for the following reaction is 6.2 * 10^-4 min^-1. How many minutes are required for 20% of a sample of cyclopropane to isomerize to propene

A certain reaction, reaction A $\rarr$ products, is first order with respect toA. Starting with [A] = 0.250M, it takes 45 min to reduce the concentration of A to 0.110M. What is its rate constant for this reaction

The isomerization of cyclopropane to propene follows first-order kinetics. At 700 K, the rate constant for this reaction is 6.2 * 10^-4 min^-1. How many minutes are required for 10.0% of a sample of cyclopropane to isomerize to propene

Benzoyl chloride, C₆H₅COCl, reacts with water to form benzoic acid, C₆H₅COOH, and hydrochloric acid. This first-order reaction is 25% complete after 26 s. How much longer would one have to wait in order to obtain 99% conversion of benzoyl chloride to benzoic acid

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day^-1. How long will it take for half of the toxin to decompose

The first-order decomposition, A $\rarr$ products, has a rate constant of 0.150 s^-1. Starting with [A]_o = 0.350 M, how much time is required for [A]_t = 0.125 M

At 25^$\circ$C the rate constant for the first-order decomposition of a pesticide solution is 6.40 *10^-3 min^-1. If the starting concentration of pesticide is 0.0314 M, what concentration will remain after 62.0 min at 25^$\circ$C

A certain first-order reaction A $\rarr$ B is 25% complete in 42 min at 25^$\circ$C. What is the half-life of the reaction