Question 1

The thermal decomposition of acetaldehyde, CH₃CHO $\rarr$CH₄ + CO, is a second-order reaction.The following data were obtained at 518°C. Calculate the rate constant for the decomposition of acetaldehyde from the above data.

Accepted Answer

The answer of The thermal decomposition of acetaldehyde, CH₃CHO $\rarr$CH₄...

Question 2

A certain reaction A $\rarr$ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

Accepted Answer

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

Question 3

The graphs below all refer to the same reaction.What is the order of this reaction?

Accepted Answer

The answer of The graphs below all refer to the...

Question 4

For what order reaction does the half-life get longer as the initial concentration increases?

Accepted Answer

In a zero order reaction, the rate is independent of the initial concentration of the reactant. This means that as the initial concentration increases, the amount of time required for half of the reactant to be consumed (i.e. the half-life) also increases. This is because the rate of the reaction remains constant, whereas the amount of reactant being consumed increases.

Question 5

Concerning the decomposition of A, A $\rarr$ products, which of the following methods could be used to determine the order of the reaction with respect to A? I.Plot [A] vs time, ln[A] vs time, and 1/[A] vs time and identify which plot yields a straight line
II.Vary the concentration of A and note by what factor the rate changes
III.Identify if successive half lives of A double, halve, or stay constant

Accepted Answer

All three methods (I, II, and III) are standard approaches to determine the order of a reaction with respect to a reactant. Method I involves graphical analysis, Method II involves observing the effect of concentration changes on the rate, and Method III involves examining the behavior of half-lives.

Question 6

For the chemical reaction A $\rarr$ C, a plot of 1/[A]_t versus time was found to give a straight line with a positive slope.What is the order of reaction?

Accepted Answer

A plot of 1/[A] versus time giving a straight line with a positive slope indicates a second-order reaction, as this is characteristic of the integrated rate law for second-order reactions.

Question 7

For the chemical reaction A $\rarr$ B + C, a plot of [A]_t versus time is found to give a straight line with a negative slope.What is the order of reaction with respect to A?

Accepted Answer

The answer of For the chemical reaction A $\rarr$ B...

Question 8

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.130 M^-1min^-1.Starting with [A]_o = 2.50 M, how many seconds will it take for [A]_t = 1.25 M

Accepted Answer

We will use the integrated rate law for a first-order reaction: ln([A]_N1)/([A]_t)) = kt Rearranging to solve for t: t = (ln([A]_N1)/([A]_t)))/k Substituting the given values: t = (ln(2.50/1.25))/(0.130 M^-1min^-1) = 185 s Therefore, the answer is (B).

Question 9

For the reaction X + Y $\rarr$Z, the reaction rate is found to depend only upon the concentration of X.A plot of 1/X verses time gives a straight line.

What is the rate law for this reaction?

Accepted Answer

The answer of For the reaction X + Y $\rarr$Z,...

Question 10

At 25°C, the second-order reaction NOCl(g) $\rarr$NO(g)+ ¹/₂Cl₂(g)is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

Accepted Answer

The answer of At 25°C, the second-order reaction NOCl(g) $\rarr$NO(g)+...

Question 11

In general, to calculate the rate constant for a first order decomposition reaction, A $\rarr$ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

Accepted Answer

The equation t1/2 = ln(2)/k is specifically for first order reactions and can be used to calculate the rate constant given the time required for the concentration to decrease by half.

Question 12

For a second order reaction, the half-life is equal to

Accepted Answer

For a second order reaction, the half-life is given by $t_{1/2} = \frac{1}{k[A]_0}$, where $k$ is the rate constant and $[A]_0$ is the initial concentration of the reactant. This matches choice C.

Question 13

In general, to calculate the activation energy for an elementary step given the rate constants at two different temperatures, which equation should be used?

Accepted Answer

The equation shown in choice C is the Arrhenius equation, which relates the rate constant (k) to the activation energy (Ea), temperature (T), and gas constant (R). By taking the logarithm of the ratio of rate constants at two different temperatures, the equation allows the activation energy to be calculated. Choices A, B, and D do not relate directly to the activation energy, while choice E is a general expression for the rate law of an elementary step but does not provide information about activation energy.

Question 14

In general, to calculate the rate constant for a second order reaction with respect to A, given an initial and final concentration as well as the time required for this change, which equation should be used?

Accepted Answer

For a second order reaction with respect to A, the equation that relates the initial concentration ([A]₀), the concentration at time t ([A]t), and the rate constant (k) is given by the integrated rate law for second order reactions: 1/[A]t = kt + 1/[A]₀.

Question 15

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.355 M^-1min^-1.Starting with [A]_o = 1.55 M, how many seconds will it take for [A]_t = 0.150M

Accepted Answer

The answer of A reaction is experimentally found to follow...

Question 16

The reaction 2NO₂(g) $\rarr$2NO(g)+ O₂(g)is suspected to be second order in NO₂.Which of the following kinetic plots would be the most useful to confirm whether or not the reaction is second order?

Accepted Answer

For a second-order reaction, a plot of [NO₂]^-1 vs. time (t) should yield a straight line.

Question 17

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M^-1s^-1, which equation should be used?

Accepted Answer

The answer of In general, to calculate the time required...

Question 18

The thermal decomposition of acetaldehyde, CH₃CHO $\rarr$CH₄ + CO, is a second-order reaction.The following data were obtained at 518°C. Based on the data given, what is the half-life for the disappearance of acetaldehyde?

Accepted Answer

The answer of The thermal decomposition of acetaldehyde, CH₃CHO $\rarr$CH₄...

Question 19

Which one of the following changes would alter the rate constant (k)for the reaction 2A + B $\rarr$ products?

Accepted Answer

The rate constant (k) is dependent on temperature according to the Arrhenius equation. Increasing the temperature will increase the rate of reaction and therefore increase the rate constant. Changes in concentration or measuring k after the reaction has run for a while will not directly affect the rate constant.

Question 20

A certain reaction A $\rarr$ products is second order with respect to A with a rate constant, k, 0.122 M^-1min^-1.Starting with [A]_o = 1.01M, how many seconds will it take for A to reach a concentration of 0.750M?

Accepted Answer

We can use the integrated rate law for a second-order reaction: 1/[A] = kt + 1/[A]0
Plugging in the given values, we get:
1/0.750 = (0.122 min^-1)(t) + 1/1.01
Solving for t, we get t = 169 seconds (or 2.81 minutes).
Therefore, the best choice is (D).

Quiz 13: Chemical Kinetics

A certain reaction A $\rarr$ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

The graphs below all refer to the same reaction.What is the order of this reaction?

For what order reaction does the half-life get longer as the initial concentration increases?

For the chemical reaction A $\rarr$ C, a plot of 1/[A]_t versus time was found to give a straight line with a positive slope.What is the order of reaction?

For the chemical reaction A $\rarr$ B + C, a plot of [A]_t versus time is found to give a straight line with a negative slope.What is the order of reaction with respect to A?

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.130 M^-1min^-1.Starting with [A]_o = 2.50 M, how many seconds will it take for [A]_t = 1.25 M

At 25°C, the second-order reaction NOCl(g) $\rarr$ NO(g) + ¹/₂Cl₂(g) is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

In general, to calculate the rate constant for a first order decomposition reaction, A $\rarr$ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

For a second order reaction, the half-life is equal to

In general, to calculate the activation energy for an elementary step given the rate constants at two different temperatures, which equation should be used?

In general, to calculate the rate constant for a second order reaction with respect to A, given an initial and final concentration as well as the time required for this change, which equation should be used?

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.355 M^-1min^-1.Starting with [A]_o = 1.55 M, how many seconds will it take for [A]_t = 0.150M

The reaction 2NO₂(g) $\rarr$ 2NO(g) + O₂(g) is suspected to be second order in NO₂.Which of the following kinetic plots would be the most useful to confirm whether or not the reaction is second order?

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M^-1s^-1, which equation should be used?

Which one of the following changes would alter the rate constant (k) for the reaction 2A + B $\rarr$ products?

A certain reaction A $\rarr$ products is second order with respect to A with a rate constant, k, 0.122 M^-1min^-1.Starting with [A]_o = 1.01M, how many seconds will it take for A to reach a concentration of 0.750M?

Quiz 13: Chemical Kinetics

The thermal decomposition of acetaldehyde, CH3CHO →\rarr→ CH4 + CO, is a second-order reaction.The following data were obtained at 518°C. Calculate the rate constant for the decomposition of acetaldehyde from the above data.

A certain reaction A →\rarr→ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

The graphs below all refer to the same reaction.What is the order of this reaction?

For what order reaction does the half-life get longer as the initial concentration increases?

For the chemical reaction A →\rarr→ C, a plot of 1/[A]t versus time was found to give a straight line with a positive slope.What is the order of reaction?

For the chemical reaction A →\rarr→ B + C, a plot of [A]t versus time is found to give a straight line with a negative slope.What is the order of reaction with respect to A?

A reaction is experimentally found to follow the rate law, Rate = k[A]2 where k = 0.130 M-1min-1.Starting with [A]o = 2.50 M, how many seconds will it take for [A]t = 1.25 M

For the reaction X + Y →\rarr→ Z, the reaction rate is found to depend only upon the concentration of X.A plot of 1/X verses time gives a straight line. What is the rate law for this reaction?

At 25°C, the second-order reaction NOCl(g) →\rarr→ NO(g) + 1/2Cl2(g) is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

In general, to calculate the rate constant for a first order decomposition reaction, A →\rarr→ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

For a second order reaction, the half-life is equal to

In general, to calculate the activation energy for an elementary step given the rate constants at two different temperatures, which equation should be used?

In general, to calculate the rate constant for a second order reaction with respect to A, given an initial and final concentration as well as the time required for this change, which equation should be used?

A reaction is experimentally found to follow the rate law, Rate = k[A]2 where k = 0.355 M-1min-1.Starting with [A]o = 1.55 M, how many seconds will it take for [A]t = 0.150M

The reaction 2NO2(g) →\rarr→ 2NO(g) + O2(g) is suspected to be second order in NO2.Which of the following kinetic plots would be the most useful to confirm whether or not the reaction is second order?

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M-1s-1, which equation should be used?

The thermal decomposition of acetaldehyde, CH3CHO →\rarr→ CH4 + CO, is a second-order reaction.The following data were obtained at 518°C. Based on the data given, what is the half-life for the disappearance of acetaldehyde?

Which one of the following changes would alter the rate constant (k) for the reaction 2A + B →\rarr→ products?

A certain reaction A →\rarr→ products is second order with respect to A with a rate constant, k, 0.122 M-1min-1.Starting with [A]o = 1.01M, how many seconds will it take for A to reach a concentration of 0.750M?

A certain reaction A $\rarr$ products is second order with respect to A.If it takes 45 min to reduce the concentration of A from 0.350 M to 0.125 M, what is the rate constant for this reaction?

For the chemical reaction A $\rarr$ C, a plot of 1/[A]_t versus time was found to give a straight line with a positive slope.What is the order of reaction?

For the chemical reaction A $\rarr$ B + C, a plot of [A]_t versus time is found to give a straight line with a negative slope.What is the order of reaction with respect to A?

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.130 M^-1min^-1.Starting with [A]_o = 2.50 M, how many seconds will it take for [A]_t = 1.25 M

At 25°C, the second-order reaction NOCl(g) $\rarr$ NO(g) + ¹/₂Cl₂(g) is 50% complete after 5.82 hours when the initial concentration of NOCl is 4.46 mol/L.How long will it take for the reaction to be 75% complete?

In general, to calculate the rate constant for a first order decomposition reaction, A $\rarr$ products, given the time needed to decrease the initial concentration by one half, which equation should be used?

A reaction is experimentally found to follow the rate law, Rate = k[A]² where k = 0.355 M^-1min^-1.Starting with [A]_o = 1.55 M, how many seconds will it take for [A]_t = 0.150M

The reaction 2NO₂(g) $\rarr$ 2NO(g) + O₂(g) is suspected to be second order in NO₂.Which of the following kinetic plots would be the most useful to confirm whether or not the reaction is second order?

In general, to calculate the time required for a given initial concentration to decrease by 35% given the rate constant with units of 1/M^-1s^-1, which equation should be used?

Which one of the following changes would alter the rate constant (k) for the reaction 2A + B $\rarr$ products?

A certain reaction A $\rarr$ products is second order with respect to A with a rate constant, k, 0.122 M^-1min^-1.Starting with [A]_o = 1.01M, how many seconds will it take for A to reach a concentration of 0.750M?