Aktiv Chemistry Chapter 12

The reaction A + B → 2 C has the rate law rate = k[A][B]³. By what factor does the rate of reaction increase when [A] remains constant but [B] is doubled?

8

What is the effect on k as the activation energy for a reaction increases? A) Increases B) Decreases C) Stays the same D) Not enough info

Decreases

Which of the following will decrease the rate of a reaction? A) Adding a catalyst to the reaction. B) Increasing the temperature. C) Decreasing the surface area of a solid reactant. D) Increasing the concentration of the reactants.

Decreasing the surface area of a solid reactant.

For the reaction 2 A + 3 B → 4 D + 5 E, how is the rate of reaction expressed in terms of rate of disappearance of B? A) ∆[B]/∆t B) -∆B/∆t C) +1/3∆[B]/∆t D) -1/3∆[B]/∆t E) +3∆[B]/∆t

-1/3∆[B]/∆t

What is the concentration of a reactant after 22.0 s if the initial concentration is 0.150 M and the rate constant is 5.4 x 10⁻² s⁻¹?

0.0457 M

How long will it take for the concentration of A to decrease from 0.500 M to 0.200 M in the first-order reaction A → B? (k = 0.800 s⁻¹)

1.15 s

A substance decomposes with a rate constant of 9.05 × 10⁻⁴ s⁻¹. How long does it take for 15.0% of the substance to decompose?

180 s

Consider the multistep reaction below. What is the balanced chemical equation of the overall reaction? A) 2 A + B + C → C + D + 2 E B) 2 A + B → 2 E C) 2 A + B → 2 E + D D) 2 A + B → D E) 2 A + B + C → D + 2 E

2 A + B → 2 E + D

What is the overall reaction order for the following rate law: Rate = k[A][B][C]²?

4

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E Which of the following equations would represent the overall reaction for this mechanism? A) A + B + D → C + E B) 4 A + B + D → B + 2C + D + E C) 2 A + B → 2 C + E D) 4 A → 2 C + E

4 A → 2 C + E

The following reaction 2CO(g) + Br₂(g) → 2COBr(g) has the rate law, rate = k[CO] [Br₂]³. The overall order of this reaction is A) 1st B) 2nd C) 3rd D) 4th E) 0th

4th

Collision theory states that as molecules or ions bump into each other, a reaction will only occur if the collision has the correct amount of energy and impact is at the right angle and location. Describe how collision theory helps predict how temperature, pressure, and concentration impact reaction rates. Bathtub cleaners used to remove hard water salts usually contain acid to help dissolve the salts. Which will remove the salts faster? A) 2.5% acid B) 3% acid C) 5% acid

5 acid

What is the half-life for a particular reaction if the rate law is rate = (1301 min⁻¹)[A]?

5.33 × 10⁻⁴ min

A first order reaction initially contains 1.00 × 10²⁰ molecules. If the reaction has a half-life of 20.0 minutes, how many molecules remain unreacted after 80.0 minutes?

6.25 × 10¹⁸ molecules

Consider the radioisotope ²³⁵U (half life = 7.04 × 10⁸ years). What is the first order rate constant for ²³⁵U?

9.84 × 10⁻¹⁰ 1/years

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E The overall reaction is 4 A → 2 C + E. Which species are intermediates in this reaction? A) B and C B) B C) B and D D) D E) C and D

B and D

An elementary reaction is known to be bimolecular. What does this mean? A) Two molecules of products are made B) The order of the reaction is 2 C) Two molecules must collide at the same time D) Both A and B E) Both B and C

Both B and C

For the reaction mechanism shown, identify the intermediate(s). A) Cl(g) B) Cl₂(g) C) HCl(g) D) CCl₃(g) E) Cl(g) and CCl₃(g)

Cl(g) and CCl₃(g)

Identify which of the following changes will result in a change in the value of the rate constant for the reaction 2 A → products A) Increasing the concentration of A B) Decreasing the concentration of A C) Increasing the temperature of the reaction D) Allowing the reaction to reach equilibrium E) Increasing the pressure

Increasing the temperature of the reaction

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E Which of the following would be the correct elementary rate law for Step 1? A) Rate = k[A] B) Rate = k[A][B] C) Rate = k[A][B][C] D) Rate = k[B][C]

Rate = k[A]

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E If Step 1 is the rate-limiting step, what would the proposed rate law for this mechanism be? A) Rate = k[A] B) Rate = k[A]²[D] C) Rate = k[A]⁴ D) Rate = k[A][B] E) Rate = k[A]²

Rate = k[A]

Determine the rate law for the reaction A + B → C + D given the following experiment data. A) Rate = k[A] B) Rate = k[A]² C) Rate = k[A][B] D) Rate = k[A]²[B] E) Rate = k[A][B]²

Rate = k[A]

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E Which of the following would be the correct elementary rate law for Step 2? A) Rate = k[A] B) Rate = k[A][B] C) Rate = k[A][B][D] D) Rate = k[A][D]

Rate = k[A][B]

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E If Step 2 is the rate-limiting step, what would the proposed rate law for this mechanism be? A) Rate = k[A] B) Rate = k[A]²[D] C) Rate = k[A]⁴ D) Rate = k[A][B] E) Rate = k[A]²/[C]

Rate = k[A]²/[C]

What is the rate law for the reaction A + B → C + D given the experimental data for four trials of initial rate? A) Rate = k[A][B] B) Rate = k[A]²[B] C) Rate = k[A][B]² D) Rate = k[A]³[B]² E) Rate = k[A]²[B]³

Rate = k[A]²[B]

A reaction mechanism has the following proposed elementary steps: Step 1: A ⇌ B + C Step 2: A + B → D Step 3: 2 A + D → C + E Which of the following would be the correct elementary rate law for Step 3? A) Rate = k[A]² B) Rate = k[A]²[D] C) Rate = k[A][D] D) Rate = k[C][E]

Rate = k[A]²[D]

Consider the multistep reaction. What is the best rate law for the overall reaction? A) Rate = k₁[A][B][C] B) Rate = k₂[C] C) Rate = k₁[A]²[B] D) Rate = (k₁[A][B])/(k₂[C]) E) Rate = k₁k₂[A]²[B]

Rate = k₁[A]²[B]

Which species has the greatest rate of appearance in the reaction below? 2 H₂S + O₂ → 2 S + 2 H₂O A) H₂S B) O₂ C) S D) H₂O E) S and H₂O have identical rates

S and H₂O have identical rates

Considering the rate law, rate = k[A]²[B], which of the following statements is correct? A) The reaction is first order in A and second order overall. B) The reaction is first order in B and second overall. C) The reaction is second order in A and second order overall. D) The reaction is first order in B and third order overall. E) The reaction is second order in A and first order overall.

The reaction is first order in B and third order overall.

Which one of the following changes could double the rate of the reaction 2 A(g) + B(g) + 3 C(g) → 3 D(g) + E(g) with the rate law Rate = k[A][B]²? A) double [A] B) double [B] C) double [C] D) cut [A] in half

double [A]

Collision theory states that as molecules or ions bump into each other, a reaction will only occur if the collision has the correct amount of energy and impact is at the right angle and location. Describe how collision theory helps predict how temperature, pressure, and concentration impact reaction rates. Pipes will react with air to oxidize. On a house that had two pipes installed for the hot water and cold water, which pipe will oxidize faster? A) hot water pipe B) cold water pipe

hot water pipe

Collision theory states that as molecules or ions bump into each other, a reaction will only occur if the collision has the correct amount of energy and impact is at the right angle and location. Describe how collision theory helps predict how temperature, pressure, and concentration impact reaction rates. As concentration increases, the number of collisions _______ and the rate of the reaction _______. A) increases; increases B) increases; decreases C) decreases; increases D) decreases; decreases

increases; increases

Collision theory states that as molecules or ions bump into each other, a reaction will only occur if the collision has the correct amount of energy and impact is at the right angle and location. Describe how collision theory helps predict how temperature, pressure, and concentration impact reaction rates. As gas reactants are compressed into a smaller volume, increasing the reactant partial pressures, the number of collisions _______ and the rate of reaction _______. A) increases; increases B) increases; decreases C) decreases; increases D) decreases; decreases

increases; increases

Collision theory states that as molecules or ions bump into each other, a reaction will only occur if the collision has the correct amount of energy and impact is at the right angle and location. Describe how collision theory helps predict how temperature, pressure, and concentration impact reaction rates. As temperature increases, the number of collisions _______ and the energy of the collisions _______. A) increases; increases B) increases; decreases C) decreases; increases D) decreases; decreases

increases; increases

The rate of a reaction increases when a catalyst has been added to the reaction mixture. The catalyst _____ A) increases the kinetic energy of the reactants. B) decreases the rate of the reverse reaction. C) increases the number of collisions between reactants. D) alters the enthalpy of reaction. E) provides a new mechanism for the reaction to proceed by.

provides a new mechanism for the reaction to proceed by.

If the reaction X + 2 Y → XY₂ occurs by the proposed mechanism, what is the rate law? A) rate = k[X] B) rate = k[Y] C) rate = k[Y]² D) rate = k[X][Y] E) rate = k[X][Y]²

rate = k[X][Y]

Identify the molecularity of the elementary reaction below: 2 A + B → C + 2 D A) Unimolecular B) Bimolecular C) Termolecular D) Cannot be determined from given mechanism

termolecular

What is the molecularity of the rate-determining step in the proposed mechanism? A) unimolecular B) bimolecular C) termolecular D) Cannot be determined from given mechanism

termolecular

All of the following are factors that affect the rate of a reaction except _____ A) the concentration of the reactants. B) presence of a catalyst. C) the magnitude of the equilibrium constant. D) the temperature of the reaction. E) the surface area of the solid reactants.

the magnitude of the equilibrium constant.