Question 1

Which one of the following sets of units is appropriate for a third-order rate constant?

Accepted Answer

For a third-order reaction, the rate constant has units of L² mol⁻² s⁻¹.

Question 2

For the reaction 3A(g) + 2B(g) → 2C(g) + 2D(g) The following data were collected at constant temperature. Determine the correct rate law for this reaction. Trial Initial [A] Initial [B] Initial Rate (mol/L) (mol/L) (mol/(L·min)) 1 0)200 0.100 6.00 × 10^-2 2 0)100 0.100 1.50 × 10^-2 3 0)200 0.200 1.20 × 10^-1 4 0)300 0.200 2.70 × 10^-1

Accepted Answer

Doubling [A] while keeping [B] constant (Trial 1 to 2) quadruples the rate, indicating second order with respect to [A]. Doubling [B] while keeping [A] constant (Trial 1 to 3) doubles the rate, indicating first order with respect to [B]. Thus, the rate law is Rate = k[A]^2[B].

Question 3

For the reaction A(g) + 2B(g) → 2C(g) + 2D(g)
The following data were collected at constant temperature. Determine the correct rate law for this reaction.
Trial Initial [A] Initial [B] Initial Rate
(mol/L) (mol/L) (mol/(L·min))
1 0)125 0.200 7.25
2 0)375 0.200 21.75
3 0)250 0.400 14.50
4 0)375 0.400 21.75

Accepted Answer

D

Question 4

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1s^-1, at what rate is [B] changing?

Accepted Answer

Using the coefficients in the balanced equation, we can determine the mole ratio of B to C as 5/8. Therefore, the rate of change of [B] can be calculated as follows:
(rate of change of [B]) = (rate of change of [C]) x (mole ratio of B to C)
(rate of change of [B]) = (4.0 mol L^-1 s^-1) x (5/8)
(rate of change of [B]) = -2.5 mol L^-1 s^-1 (Note the negative sign indicates that [B] is decreasing)

Question 5

For the reaction A(g) + 2B(g) → 2C(g) + 2D(g)
The following data were collected at constant temperature. Determine the correct rate law for this reaction.
Trial Initial [A] Initial [B] Initial Rate
(mol/L) (mol/L) (mol/(L·min))
1 0)125 0.200 7.25
2 0)375 0.200 21.75
3 0)250 0.400 14.50
4 0)375 0.400 21.75

Accepted Answer

The answer of For the reaction A(g) + 2B(g) →...

Question 6

A study of the decomposition reaction 3RS₂ → 3R + 6S yields the following initial rate data. [RS₂](mol L^-1) Rate (mol/(L·s)) 0)150 0.0394 0)250 0.109 0)350 0.214 0)500 0.438 What is the rate constant for the reaction?

Accepted Answer

The answer of A study of the decomposition reaction 3RS₂...

Question 7

Consider the general reaction 5Br^-(aq) + BrO₃^-(aq) + 6H⁺(aq) → 3Br₂(aq) + 3H₂O(aq) For this reaction, the rate when expressed as Δ[Br₂]/Δt is the same as

Accepted Answer

The answer of Consider the general reaction 5Br^-(aq) + BrO₃^-(aq)...

Question 8

Which one of the following sets of units is appropriate for a second-order rate constant?

Accepted Answer

A second-order rate constant has units of L/mol*s. Therefore, the appropriate set of units would have liters, moles, and seconds in its denominator and numerator. Option C has these units. The other options do not have the correct combination of units or have extra units that are not necessary.

Question 9

When the reaction A → B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

Accepted Answer

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

Question 10

2NOBr(g) → 2NO(g) + Br₂(g) [NOBr](mol L^-1) Rate (molL^-1s^-1) 0)0450 1.62 × 10^-3 0)0310 7.69 × 10^-4 0)0095 7.22 × 10^-5 Based on the initial rate data above, what is the value of the rate constant?

Accepted Answer

The answer of 2NOBr(g) → 2NO(g) + Br₂(g) [NOBr](mol L^-1)...

Question 11

When the reaction A → B + C is studied, a plot of ln[A]_t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Accepted Answer

The fact that the plot of ln[A] vs. time gives a straight line with a negative slope indicates that the reaction is first order.

Question 12

Sulfuryl chloride, SO₂Cl₂(g), decomposes at high temperature to form SO₂(g) and Cl₂(g). The rate constant at a certain temperature is 4.68 × 10^-⁵s^-1. What is the order of the reaction?

Accepted Answer

Since the equation only has one reactant (Sulfuryl chloride), the reaction must be a first-order reaction.

Question 13

The compound RX3 decomposes according to the equation 3RX₃ → R + R₂X₃ + 3X₂ In an experiment the following data were collected for the decomposition at 100°C. What is the average rate at which RX₃ is disappearing over the entire experiment? T(s) [RX₃](mol L^-1) 0 0.85 2 0.67 6 0.41 8 0.33 12 0.20 14 0.16

Accepted Answer

To find the rate at which RX₃ is disappearing, we need to calculate the average rate of reaction over the entire experiment. We can use the following formula to calculate the average rate of reaction: Average rate = (Change in concentration)/(Change in time) We can use the data given in the table to find the change in concentration of RX₃ over different time intervals. For the first time interval (0 to 2 seconds), the change in concentration of RX₃ is: Change in [RX₃] = 0.85 mol L^-1 - 0.67 mol L^-1 = 0.18 mol L^-1 Change in time = 2 seconds - 0 seconds = 2 seconds Average rate for first time interval = (0.18 mol L^-1)/(2 seconds) = 0.09 mol L^-¹s^-¹ Similarly, we can calculate the average rates for other time intervals and take their average to get the overall average rate for the entire experiment. Average rate = (0.09 mol L^-¹s^-¹ + 0.06 mol L^-¹s^-¹ + 0.03 mol L^-¹s^-¹ + 0.02 mol L^-¹s^-¹ + 0.04 mol L^-¹s^-¹ + 0.02 mol L^-¹s^-¹)/6 seconds = 0.26/6 mol L^-¹s^-¹ = 0.043 mol L^-¹s^-¹ Rounding off to two significant figures, we get the answer as 0.049 mol L^-¹s^-¹. Therefore, the best choice is D.

Question 14

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of -0.208 hr^-1 results. What is the rate law for the reaction?

Accepted Answer

The straight line of ln [sucrose] vs. time indicates a first-order reaction, and the rate constant is the absolute value of the slope, 0.208 hr^-1.

Question 15

A reaction has the following rate law: Rate = k[A][B]₂ In experiment 1, the concentrations of A and B are both 0.10 mol L^-1; in experiment 2, the concentrations are both 0.30 mol L^-1. If the temperature stays constant, what is the value of the ratio, Rate(2)/Rate(1)?

Accepted Answer

The ratio of rates is directly proportional to the ratio of [A][B]. In this case, the ratio of [A][B] in experiment 2 compared to experiment 1 is 3, since both concentrations tripled. Therefore, the ratio of rates is also 3^(1+1+2+0) = 27. So the answer is E.

Question 16

Consider the reaction 2NH₃(g) → N₂(g) + 3H₂(g) If the rate Δ[H₂]/Δt is 0.030 mol L_-1s_-1, then Δ[NH₃ ]/Δt is

Accepted Answer

The stoichiometry of the reaction shows that 3 moles of H₂ are produced for every 2 moles of NH₃ consumed. Therefore, the rate of consumption of NH₃ is (2/3) times the rate of production of H₂, which is (2/3) * 0.030 mol L⁻¹s⁻¹ = 0.020 mol L⁻¹s⁻¹. Since NH₃ is being consumed, the rate is negative: -0.020 mol L⁻¹s⁻¹.

Question 17

Which of the following sets of units could be appropriate for a zero-order rate constant?

Accepted Answer

A zero-order rate constant has units of concentration per time or mol L-1 s-1, which is represented by the units mol L^-1s^-1. Therefore, the appropriate set of units is E.

Question 18

For the reaction 2A + B + 2C → D + E
The following initial rate data were collected at constant temperature. Determine the correct rate law for this reaction. All units are arbitrary.
Trial [A] [B] [C] Rate
1 0)225 0.150 0.350 0.0217
2 0)320 0.150 0.350 0.0439
3 0)225 0.250 0.350 0.0362
4 0)225 0.150 0.600 0.01270

Accepted Answer

The rate doubles when [A] is increased from 0.225 to 0.320, indicating a first-order dependence on [A]. The rate increases when [B] is increased, indicating a first-order dependence on [B]. The rate decreases when [C] is increased, indicating an inverse first-order dependence on [C]. Thus, the rate law is Rate = k[A]^2[B][C]^-1.

Question 19

Sulfur trioxide can undergo decomposition according to the equation 2SO₃ → 2SO₂ + O₂ For this reaction, rate = -0.5Δ[SO₃ ]/Δt = k[SO₃]². If the reaction rate is 1.75 × 10^-7 mol L^-1 min^-1 when the concentration of sulfur trioxide is 5.4 × 10^-3 mol L^-1, what is the value of the rate constant k?

Accepted Answer

The answer of Sulfur trioxide can undergo decomposition according to...

Question 20

Ammonium cyanate (NH₄CNO) reacts to form urea (NH₂CONH₂). At 65°C the rate constant, k, is 3.60 L mol^-1s^-1.What is the rate law for this reaction?

Accepted Answer

The rate law for this reaction is determined by the experimentally measured rate constant and the concentrations of the reactants. From the given information, we know that the rate constant (k) is 3.60 L mol^-1 s^-1. The reaction involves only one reactant, ammonium cyanate (NH₄CNO), which means that the rate law must only involve this reactant. The rate law for the reaction can be expressed as: Rate = k [NH₄CNO]^x where x is the order of the reaction with respect to NH₄CNO. To determine x, we need to run the reaction at different concentrations of NH₄CNO and measure the corresponding rates. Since x cannot be determined from the given information, we should look at the answer choices to see which one(s) make sense. Choice B is the best choice because it includes NH₄CNO raised to a power of 2 (²), which suggests that the reaction is second order with respect to NH₄CNO. This makes sense because the product, urea, contains two NH₄CNO molecules. Choice A is incorrect because it only includes NH₄CNO without any indication of the order of the reaction. Choice C is incorrect because it includes a concentration unit of mol L^-1, which is not consistent with the units of the rate constant (L mol^-1 s^-1). Choice D is incorrect because it includes both NH₄CNO and urea, which is not appropriate for a rate law that only involves one reactant. Choice E is incorrect because it includes urea, which is a product and not a reactant.

Quiz 16: Kinetics Rates and Mechanisms of Chemical Reactions

Which one of the following sets of units is appropriate for a third-order rate constant?

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1s^-1, at what rate is [B] changing?

A study of the decomposition reaction 3RS₂ → 3R + 6S yields the following initial rate data. [RS₂](mol L^-1) Rate (mol/(L·s) ) 0) 150 0.0394 0) 250 0.109 0) 350 0.214 0) 500 0.438 What is the rate constant for the reaction?

Consider the general reaction 5Br^-(aq) + BrO₃^-(aq) + 6H⁺(aq) → 3Br₂(aq) + 3H₂O(aq) For this reaction, the rate when expressed as Δ[Br₂]/Δt is the same as

Which one of the following sets of units is appropriate for a second-order rate constant?

When the reaction A → B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

2NOBr(g) → 2NO(g) + Br₂(g) [NOBr](mol L^-1) Rate (molL^-1s^-1) 0) 0450 1.62 × 10^-3 0) 0310 7.69 × 10^-4 0) 0095 7.22 × 10^-5 Based on the initial rate data above, what is the value of the rate constant?

When the reaction A → B + C is studied, a plot of ln[A]_t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Sulfuryl chloride, SO₂Cl₂(g) , decomposes at high temperature to form SO₂(g) and Cl₂(g) . The rate constant at a certain temperature is 4.68 × 10^-⁵s^-1. What is the order of the reaction?

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of -0.208 hr^-1 results. What is the rate law for the reaction?

A reaction has the following rate law: Rate = k[A][B]₂ In experiment 1, the concentrations of A and B are both 0.10 mol L^-1; in experiment 2, the concentrations are both 0.30 mol L^-1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Consider the reaction 2NH₃(g) → N₂(g) + 3H₂(g) If the rate Δ[H₂]/Δt is 0.030 mol L_-1s_-1, then Δ[NH₃ ]/Δt is

Which of the following sets of units could be appropriate for a zero-order rate constant?

Ammonium cyanate (NH₄CNO) reacts to form urea (NH₂CONH₂) . At 65°C the rate constant, k, is 3.60 L mol^-1s^-1.What is the rate law for this reaction?

Quiz 16: Kinetics Rates and Mechanisms of Chemical Reactions

Which one of the following sets of units is appropriate for a third-order rate constant?

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L-1s-1, at what rate is [B] changing?

A study of the decomposition reaction 3RS2 → 3R + 6S yields the following initial rate data. [RS2](mol L-1) Rate (mol/(L·s) ) 0) 150 0.0394 0) 250 0.109 0) 350 0.214 0) 500 0.438 What is the rate constant for the reaction?

Consider the general reaction 5Br-(aq) + BrO3-(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(aq) For this reaction, the rate when expressed as Δ[Br2]/Δt is the same as

Which one of the following sets of units is appropriate for a second-order rate constant?

When the reaction A → B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. What is the order of the reaction?

2NOBr(g) → 2NO(g) + Br2(g) [NOBr](mol L-1) Rate (molL-1s-1) 0) 0450 1.62 × 10-3 0) 0310 7.69 × 10-4 0) 0095 7.22 × 10-5 Based on the initial rate data above, what is the value of the rate constant?

When the reaction A → B + C is studied, a plot of ln[A]t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Sulfuryl chloride, SO2Cl2(g) , decomposes at high temperature to form SO2(g) and Cl2(g) . The rate constant at a certain temperature is 4.68 × 10-5s-1. What is the order of the reaction?

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of -0.208 hr-1 results. What is the rate law for the reaction?

A reaction has the following rate law: Rate = k[A][B]2 In experiment 1, the concentrations of A and B are both 0.10 mol L-1; in experiment 2, the concentrations are both 0.30 mol L-1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Consider the reaction 2NH3(g) → N2(g) + 3H2(g) If the rate Δ[H2]/Δt is 0.030 mol L-1s-1, then Δ[NH3 ]/Δt is

Which of the following sets of units could be appropriate for a zero-order rate constant?

Sulfur trioxide can undergo decomposition according to the equation 2SO3 → 2SO2 + O2 For this reaction, rate = -0.5Δ[SO3 ]/Δt = k[SO3]2. If the reaction rate is 1.75 × 10-7 mol L-1 min-1 when the concentration of sulfur trioxide is 5.4 × 10-3 mol L-1, what is the value of the rate constant k?

Ammonium cyanate (NH4CNO) reacts to form urea (NH2CONH2) . At 65°C the rate constant, k, is 3.60 L mol-1s-1.What is the rate law for this reaction?

Consider the following reaction 8A(g) + 5B(g) → 8C(g) + 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1s^-1, at what rate is [B] changing?

A study of the decomposition reaction 3RS₂ → 3R + 6S yields the following initial rate data. [RS₂](mol L^-1) Rate (mol/(L·s) ) 0) 150 0.0394 0) 250 0.109 0) 350 0.214 0) 500 0.438 What is the rate constant for the reaction?

Consider the general reaction 5Br^-(aq) + BrO₃^-(aq) + 6H⁺(aq) → 3Br₂(aq) + 3H₂O(aq) For this reaction, the rate when expressed as Δ[Br₂]/Δt is the same as

When the reaction A → B + C is studied, a plot 1/[A]_t vs. time gives a straight line with a positive slope. What is the order of the reaction?

2NOBr(g) → 2NO(g) + Br₂(g) [NOBr](mol L^-1) Rate (molL^-1s^-1) 0) 0450 1.62 × 10^-3 0) 0310 7.69 × 10^-4 0) 0095 7.22 × 10^-5 Based on the initial rate data above, what is the value of the rate constant?

When the reaction A → B + C is studied, a plot of ln[A]_t vs. time gives a straight line with a negative slope. What is the order of the reaction?

Sulfuryl chloride, SO₂Cl₂(g) , decomposes at high temperature to form SO₂(g) and Cl₂(g) . The rate constant at a certain temperature is 4.68 × 10^-⁵s^-1. What is the order of the reaction?

Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of -0.208 hr^-1 results. What is the rate law for the reaction?

A reaction has the following rate law: Rate = k[A][B]₂ In experiment 1, the concentrations of A and B are both 0.10 mol L^-1; in experiment 2, the concentrations are both 0.30 mol L^-1. If the temperature stays constant, what is the value of the ratio, Rate(2) /Rate(1) ?

Consider the reaction 2NH₃(g) → N₂(g) + 3H₂(g) If the rate Δ[H₂]/Δt is 0.030 mol L_-1s_-1, then Δ[NH₃ ]/Δt is

Ammonium cyanate (NH₄CNO) reacts to form urea (NH₂CONH₂) . At 65°C the rate constant, k, is 3.60 L mol^-1s^-1.What is the rate law for this reaction?