Chemical Kinetics

The following reaction is second order with respect to A and zero order with respect to B. Identify the correct rate expression. 2A + B → C + 2D A. rate = k[A]² B. rate = k[A]²[B] C. rate = k[A]⁴ D. rate = k[2A]²

A

What is the rate law for this reaction? A. rate = k[I⁻][S₂O₈²⁻] B. rate = k[I⁻]¹₋⁵[S₂O₈²⁻] C. rate = k[I⁻]³[S₂O₈²⁻] D. rate = k[I⁻]²[S₂O₈²⁻]

A

What was the change in time (delta t) for Trial 1? Choose the closest answer. A. 20 s B. 11 s C. 33 s D. 28 s

A

What was the rate of reaction in Trial 1? Choose the closest answer. A. 3.85 x 10⁻⁵ M s⁻¹ B. 3.99 x 10⁻⁵ M s⁻¹ C. 3.13 x 10⁻⁵ M s⁻¹ D. 4.15 x 10⁻⁵ M s⁻¹

A

What was the rate of reaction in Trial 3? Choose the closest answer. A. 8.84 x 10⁻⁶ M s⁻¹ B. 7.86 x 10⁻⁶ M s⁻¹ C. 6.98 x 10⁻⁶ M s⁻¹ D. 9.55 x 10⁻⁶ M s⁻¹

A

What was the rate of reaction in Trial 4? Choose the closest answer. A. 1.83 x 10⁻⁵ M s⁻¹ B. 2.13 x 10⁻⁵ M s⁻¹ C. 1.75 x 10⁻⁵ M s⁻¹ D. 1.92 x 10⁻⁵ M s⁻¹

A

The iodine clock experiment, which consists of the following three reactions, is set up so [S₂O₃²⁻] < [S₂O₈²⁻]. What would happen if [S₂O₃²⁻] > [S₂O₈²⁻]? Reaction 1: 3I⁻ (aq) + S₂O₈²⁻ (aq) → I₃⁻ (aq) + 2SO₄²⁻ (aq) slow Reaction 2: I₃⁻ (aq) + 2S₂O₃²⁻ (aq) → 3I⁻ (aq) + S₄O₆²⁻ (aq) fast Reaction 3: I₃⁻ (aq) + starch (aq) → 3I⁻ ---- starch (bluish black) fast A. The bluish black color would be darker because more S₂O₃²⁻ is present. B. No bluish black color would form because all the I₃⁻ formed in reaction 1 would be converted back into I⁻. C. The bluish black color would be darker because more S₂O₃²⁻ is present. D. No bluish black color would form because all the I⁻ formed in reaction 1 would be converted back into I₃⁻.

B

What is the average rate constant? Choose the closest answer. A. 5.73 x 10⁻³ L/(mol s) B. 6.16 x 10⁻³ L/(mol s) C. 6.88 x 10⁻³ L/(mol s) D. 5.44 x 10⁻³ L/(mol s)

B

What is the order of peroxodisulfate in the rate expression? A. 0 B. 1 C. 1.5 D. 2

B

What was the change in time (delta t) for Trial 3? Choose the closest answer. A. 82 s B. 87 s C. 78 s D. 72 s

B

What was the concentration of iodide in Trial 4? A. 0.0305 M B. 0.0385 M C. 0.0460 M D. 0.0411 M

B

What was the concentration of peroxodisulfate in Trial 2? A. 0.0302 M B. 0.0385 M C. 0.0488 M D. 0.0418 M

B

What was the rate of reaction in Trial 2? Choose the closest answer. A. 1.95 x 10⁻⁵ M s⁻¹ B. 1.83 x 10⁻⁵ M s⁻¹ C. 2.15 x 10⁻⁵ M s⁻¹ D. 1.55 x 10⁻⁵ M s⁻¹

B

What was the rate of reaction in Trial 5? Choose the closest answer. A. 9.75 x 10⁻⁶ M s⁻¹ B. 8.74 x 10⁻⁶ M s⁻¹ C. 8.02 x 10⁻⁶ M s⁻¹ D. 9.15 x 10⁻⁶ M s⁻¹

B

What was the total volume of each reaction? A. 60 mL B. 65 mL C. 75 mL D. 70 mL

B

A plot of log(rate) versus log[A] yields the following linear equation. What order is the reaction with respect to A? y = 2x + 3.1 A. 5 B. 1.5 C. 2 D. 3

C

A student conducting the iodine clock experiment accidentally makes an S₂O₃²⁻ stock solution that is too concentrated. How will this affect the rate measurement? Reaction 1: 3I⁻ (aq) + S₂O₈²⁻ (aq) → I₃⁻ (aq) + 2SO₄²⁻ (aq) slow Reaction 2: I₃⁻ (aq) + 2S₂O₃²⁻ (aq) → 3I⁻ (aq) + S₄O₆²⁻ (aq) fast Reaction 3: I₃⁻ (aq) + starch (aq) → 3I⁻ ---- starch (bluish black) fast A. It will take less time for the color to change, which will decrease delta t, resulting in a higher calculated rate. B. It will take longer for the color to change, which will increase delta t, resulting in a higher calculated rate. C. It will take longer for the color to change, which will increase delta t, resulting in a lower calculated rate. D. It will take less time for the color to change, which will increase delta t, resulting in a lower calculated rate.

C

If 2.3 x 10⁻³ M product forms in 46 seconds, what is the rate of the reaction? A. 2.3 x 10⁻³ M/s B. 2.0 x 10⁴ M/s C. 5.0 x 10⁻⁵ M/s D. 50 M/s

C

The iodine clock experiment consists of the following three reactions, where reaction 1 is slow relative to reactions 2 and 3. Predict what would happen if reaction 2 was slow relative to reaction 1 (assume that reaction 3 is still fast). Reaction 1: 3I⁻ (aq) + S₂O₈²⁻ (aq) → I₃⁻ (aq) + 2SO₄²⁻ (aq) slow Reaction 2: I₃⁻ (aq) + 2S₂O₃²⁻ (aq) → 3I⁻ (aq) + S₄O₆²⁻ (aq) fast Reaction 3: I₃⁻ (aq) + starch (aq) → 3I⁻ ---- starch (bluish black) fast A. The reaction would turn blue slower because I₃⁻ is removed at a slower rate. B. Reaction 3 would not occur. C. A color change would appear immediately because I₃⁻ would be removed slowly from solution, and would therefore be able to react with starch. D. The rate of color change would indicate the rate of reaction 3 instead of reaction 1.

C

What is the overall reaction order for a reaction with the following rate expression? rate = k[A]²[B] A. 2 B. 1 C. 3 D. 4

C

What was the change in time (delta t) for Trial 4? Choose the closest answer. A. 50 s B. 33 s C. 42 s D. 23 s

C

What was the change in time (delta t) for Trial 5? Choose the closest answer. A. 60 s B. 70 s C. 88 s D. 98 s

C

What was the concentration of iodide in Trial 1? A. 0.0571 M B. 0.0659 M C. 0.0769 M D. 0.0869 M

C

A plot of log(delta [I₃⁻] / delta t) versus log [I⁻]₀ from data in Trials 1, 4, and 5 is shown below. Determine the value of p from the graph. A. 1.5 B. 0.5 C. 2 D. 1

D

A student conducting the iodine clock experiment accidentally makes an S₂O₈²⁻ stock solution that is too concentrated. How will this affect the rate measurement? Reaction 1: 3I⁻ (aq) + S₂O₈²⁻ (aq) → I₃⁻ (aq) + 2SO₄²⁻ (aq) slow Reaction 2: I₃⁻ (aq) + 2S₂O₃²⁻ (aq) → 3I⁻ (aq) + S₄O₆²⁻ (aq) fast Reaction 3: I₃⁻ (aq) + starch (aq) → 3I⁻ ---- starch (bluish black) fast A. Not all of the 2S₂O₃²⁻ will react, which will increase the calculated rate. B. Not all of the 2S₂O₃²⁻ will react, which will decrease the calculated rate. C. It will take longer for the color to change, as the reaction takes longer when more reactant is present. D. It will take less time for the color to change, as rate increases with concentration of reactant.

D

For a zero order reaction, if the concentration of reactant is increased 4-fold, the reaction rate A. increases 16-fold. B. increases 8-fold. C. increases four-fold. D. remains the same.

D

The following reaction is first order. If the rate at [A] = 0.1 M is 3, what will the rate be at [A] = 0.2 M? A → B + C A. 9 B. 4 C. 3 D. 6

D

What is the order of iodide in the rate expression? A. 3 B. 2 C. 0 D. 1

D

What was the change in time (delta t) for Trial 2? Choose the closest answer. A. 50 s B. 77 s C. 34 s D. 42 s

D

What was the concentration of iodide in Trial 5? A. 0.0282 M B. 0.0128 M C. 0.0202 M D. 0.0192 M

D

What was the concentration of peroxodisulfate in Trial 1? A. 0.0879 M B. 0.0569 M C. 0.0669 M D. 0.0769 M

D

What was the concentration of peroxodisulfate in Trial 3? A. 0.0132 M B. 0.0212 M C. 0.0075 M D. 0.0192 M

D

What was the initial concentration of thiosulfate? A. 0.00077 M B. 0000134 M C. 0.00165 M D. 0.00154 M

D