Question 1

The reaction A + 2B → products has been found to have the rate law,rate = k[A][B]².While holding the concentration of A constant,the concentration of B is increased to three times its initial value.By what factor does the rate of reaction increase? A)3 B)6 C)9 D)27 E)30

Accepted Answer

The rate law is rate = k[A][B]^2. If [B] is increased to three times its initial value, the rate becomes k[A](3[B])^2 = 9k[A][B]^2, meaning the rate increases by a factor of 9.

Question 2

The reaction A + 2B → products was found to follow the rate law: rate = k[A]²[B].Predict by what factor the rate of reaction will increase when the concentration of A is doubled,the concentration of B is tripled,and the temperature remains constant. A)5 B)6 C)12 D)18 E)None of these

Accepted Answer

Given rate law: rate = k[A]^1[U]^1[P1]^2[S1]^1[P0]^1[B]^1
When [A] is doubled, the rate becomes: rate' = k[2A]^1[U]^1[P1]^2[S1]^1[P0]^1[B]^1
= 2k[A]^1[U]^1[P1]^2[S1]^1[P0]^1[B]^1
When [B] is tripled, the rate becomes: rate'' = k[A]^1[U]^1[P1]^2[S1]^1[P0]^1[3B]^1
= 3k[A]^1[U]^1[P1]^2[S1]^1[P0]^1[B]^1
Thus, the overall increase in rate is: rate'' / rate = (3k/2k) = 1.5 = 12/8
Therefore, the rate of reaction will increase by a factor of 12/8 = 1.5 or 3/2. Hence the answer is C.

Question 3

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^-5 s^-1.What is the order of the reaction? A)Zero B)First C)Second D)Third E)More information is needed to determine the overall order.

Accepted Answer

The reaction is decomposing into two products, so it is a first-order reaction. This is supported by the rate constant being given as a first-order rate constant (s^-1).

Question 4

For the reaction BrO₃^- + 5Br^- + 6H⁺ → 3Br² + 3H₂O at a particular time,-Δ[BrO₃^-]/Δt = 1.5 × 10^-2 M/s.What is -Δ[Br^-]/Δt at the same instant? A)13 M/s B)7.5 × 10^-2 M/s C)1.5 × 10^-2 M/s D)3.0 × 10^-3 M/s E)330 M/s

Accepted Answer

The rate of disappearance of Br⁻ is five times the rate of disappearance of BrO₃⁻ because the stoichiometry of the reaction shows that 5 moles of Br⁻ react with 1 mole of BrO₃⁻. Therefore, -Δ[Br⁻]/Δt = 5 × 1.5 × 10⁻² M/s = 7.5 × 10⁻² M/s.

Question 5

Consider the general reaction 5Br-(aq)+ Br O₃-(aq)+ 6H+(aq)→ 3Br₂(aq)+ 3 H₂O(aq) For this reaction,which is equal to Δ[Br2]/Δt? A)-Δ[H₂O]/Δt B)3Δ[Br O₃^-]/Δt C)-5Δ[Br^-]/Δt D)-0.6Δ[Br^-]/Δt E)None of these choices is correct.

Accepted Answer

The rate of formation of Br2 is related to the rate of consumption of Br- by the stoichiometry of the reaction. Since 5 moles of Br- produce 3 moles of Br2, the rate of formation of Br2 is (3/5) times the rate of consumption of Br-, which simplifies to 0.6.

Question 6

For the reaction A + 2B → C,which expression is correct?
A)Δ[C]/Δt = Δ[A]/Δt
B)Δ[C]/Δt = 2Δ[B]/Δt
C)Δ[C]/Δt = -2Δ[B]/Δt
D)Δ[C]/Δt = -½Δ[B]/Δt
E)Δ[C]/Δt = -½Δ[A]/Δt

Accepted Answer

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

Question 7

What is the name given for the study of how fast reactions take place?
A)Reaction rate
B)Activation energy
C)Chemical kinetics
D)Reactivity
E)Half-life

Accepted Answer

Chemical kinetics is the study of how fast chemical reactions occur, including factors that affect the rate of reaction, mechanisms of chemical reactions, and reaction pathways.

Question 8

For the hypothetical reaction A + 3B → 2C,the rate should be expressed as
A)rate = Δ[A]/Δt.
B)rate = -Δ[C]/Δt.
C)rate = -3(Δ[B]/Δt).
D)rate = (1/2)(Δ[C]/Δt).
E)rate = (1/3)(Δ[B]/Δt).

Accepted Answer

The rate of a reaction is often expressed in terms of the change in concentration of products over time. For the given reaction, A + 3B → 2C, the rate can be expressed as the change in concentration of C over time, divided by the stoichiometric coefficient of C in the balanced equation. Since 2 moles of C are produced, the rate is (1/2)(Δ[C]/Δt), which accounts for the stoichiometry of the reaction.

Question 9

Consider the following reaction 8A(g)+ 5B(g)→ 8C(g)+ 6D(g) If [C] is increasing at the rate of 4.0 mol L^-1 • s^-1,at what rate is [B] changing? A)-0.40 mol L^-1• s^-1 B)-2.5 mol L^-1• s^-1 C)-4.0 mol L^-1• s^-1 D)-5.0 mol L^-1• s^-1 E)-6.4 mol L^-1• s^-1

Accepted Answer

We can use the following expression to relate the rates of change of reactants and products in a chemical reaction: rate of change of [X] = - (stoichiometric coefficient of X in the reaction) x (rate of reaction) Using this expression, we can write: rate of change of [B] = - (5/8) x (rate of reaction) We are given that the rate of change of [C] is 4.0 mol L^-1 s^-1. The stoichiometric coefficient of C in the reaction is 8, so: rate of reaction = (1/8) x (rate of change of [C]) = 0.5 mol L^-1 s^-1 Substituting this value into the expression for the rate of change of [B], we get: rate of change of [B] = - (5/8) x (0.5 mol L^-1 s^-1) = -0.3125 mol L^-1 s^-1 Rounding this to two significant figures, we get -0.31 mol L^-1 s^-1, which is closest to option B (-2.5 mol L^-1• s^-1 after conversion to mol L^-1 s^-1).

Question 10

For the reaction C₆H₁₄(g)→ C₆H₆(g)+ 4H₂(g),ΔP(H₂)/Δt was found to be 2.5 × 10^-2 atm/s, where ΔP(H₂)is the change in pressure of hydrogen.Determine ΔP(C₆H₁₄)/Δt for this reaction at the same time. A)2.5 × 10^-2 atm/s B)-6.3 × 10^-3 atm/s C)-2.5 × 10^-2 atm/s D)0.10 atm/s E)6.3 × 10^-3 atm/s

Accepted Answer

Given the stoichiometry of the reaction, for every 4 moles of H2 produced, 1 mole of CH4 is consumed. Therefore, the rate of change in pressure for CH4 will be one-fourth that of H2 but in the opposite direction (negative), making it -2.5 × 10^-2 atm/s ÷ 4 = -6.25 × 10^-3 atm/s, which is closest to choice B.

Question 11

What is the rate expression for the production of X,which is a gas,at constant volume? A)rate = P_gVΔ[X]/RΔt B)rate = -TΔ[X]/P_gVΔt C)rate = -P_gV(Δ[X]/TΔt) D)rate = (1/RT)(ΔP_X/Δt) E)rate = (1/RΔP_X)(VT/Δt)

Accepted Answer

The rate expression for the production of a gas at constant volume is given by the equation: rate = (1/RT) (ΔP/Δt) where P = pressure of the gas, T = temperature, R = gas constant, and ΔP/Δt is the rate of change of pressure over time. In this case, X is a gas, so the best choice is D, which has the same form as the rate expression for a gas at constant volume. Therefore, the answer is D.

Question 12

The rate constant for a reaction is 4.65 L • mol^-1 • s^-1.What is the overall order of the reaction? A)Zero B)First C)Second D)Third E)More information is needed to determine the overall order.

Accepted Answer

The overall order of the reaction is the sum of the orders with respect to each reactant. In this case, the order is 1+1-1-1 = 0, which would suggest that the reaction is zero order. However, the presence of units in the rate constant (L/mol/s) indicates that the rate is dependent on the concentrations of the reactants, and therefore the reaction must be at least first order. The units also suggest that the reaction may be second order overall (first order with respect to each of two reactants). The negative order with respect to two of the reactants suggests that their presence actually slows the reaction down. Therefore, the correct answer is (C) second order.

Question 13

Consider the reaction 2NH₃(g)→ N₂(g)+ 3 H₂ (g) If the rate Δ[H₂]/Δt is 0.030 mol L^-1 • s^-1,what is Δ[N H₃]/Δt? A)-0.045 mol L^-1• s^-1 B)-0.030 mol L^-1• s^-1 C)-0.020 mol L^-1• s^-1 D)-0.010 mol L^-1• s^-1 E)None of these choices is correct.

Accepted Answer

The answer of Consider the reaction 2NH₃(g)→ N₂(g)+ 3 H₂...

Question 14

Which equation best describes the average rate for the reaction shown? A(aq)+ B(aq)→ C(aq)+ D(aq)
A)rate = [C][D]
[A][B]
B)rate = +Δ[B]/Δt
C)rate = -Δ[C]/Δt
D)rate = -Δ[A]/Δt
E)rate = [A][B]
[C][D]

Accepted Answer

The rate of the reaction can be determined by measuring the change in concentration of any reactant or product over time. Therefore, the best equation to describe the average rate of this reaction is rate = -Δ[A]/Δt or rate = -Δ[B]/Δt, since the concentration of either A or B is decreasing as the reaction proceeds. The other options do not accurately describe the rate of the reaction.

Question 15

For the following reaction,ΔP(C₆H₁₄)/Δt was found to be -6.2 × 10^-3 atm/s. C₆H₁₄(g)→ C₆H₆(g)+ 4H₂(g) Determine ΔP(H₂)/Δt for this reaction at the same time. A)6.2 × 10^-3 atm/s B)1.6 × 10^-3 atm/s C)2.5 × 10^-2 atm/s D)-1.6 × 10^-3 atm/s E)-2.5 × 10^-2 atm/s

Accepted Answer

For every mole of $ \text{CS}_2 $ that reacts, 4 moles of $ \text{H}_2 $ are produced. Therefore, if the rate of disappearance of $ \text{CS}_2 $ is $ -6.2 \times 10^{-3} $ atm/s, the rate of appearance of $ \text{H}_2 $ is 4 times that rate, which is $ 4 \times -6.2 \times 10^{-3} = -24.8 \times 10^{-3} $ atm/s. Since the rate of appearance is positive, the correct answer is $ 2.5 \times 10^{-2} $ atm/s after adjusting the decimal place correctly.

Question 16

What are possible units for the reaction rate? A)L • mol^-1 • s^-1 B)L² • mol^-2 • s^-1 C)s^-1 D)s^-2 E)mol • L^-1 • s^-1

Accepted Answer

The answer of What are possible units for the reaction...

Question 17

The reaction A + 2B → products has the rate law,rate = k[A][B]³.If the concentration of B is doubled while that of A is unchanged,by what factor will the rate of reaction increase? A)2 B)4 C)6 D)8 E)9

Accepted Answer

The rate law is rate = k[A][B]^3. If [B] is doubled, the rate becomes k[A](2[B])^3 = 8k[A][B]^3, so the rate increases by a factor of 8.

Question 18

The reaction A + 2B → products was found to have the rate law,rate = k[A][B]².Predict by what factor the rate of reaction will increase when the concentration of A is doubled and the concentration of B is also doubled. A)2 B)4 C)6 D)8 E)9

Accepted Answer

Doubling [A] doubles the rate, and doubling [B] quadruples the rate (since rate is proportional to [B]^2). Therefore, the overall rate increases by a factor of 2 * 4 = 8.

Question 19

Which is the correct unit for a first-order rate constant? A)s^-1 B)M • s^-1 C)M • s D)M^-1 • s^-1 E)M^-2 • s^-1

Accepted Answer

For a first-order reaction, the rate constant has units of s^-1 because the rate is proportional to the concentration of a single reactant raised to the first power.

Question 20

For the overall chemical reaction shown below,which one of the following statements can be rightly assumed? 2 H₂S(g)+ O₂(g)→ 2S(s)+ 2H₂O(l) A)The reaction is third-order overall. B)The reaction is second-order overall. C)The rate law is: rate = k[H₂S]² [O₂]. D)The rate law is: rate = k[H₂S] [O₂]. E)The rate law cannot be determined from the information given.

Accepted Answer

The rate law cannot be determined from the stoichiometry of the reaction alone; it must be determined experimentally.

Quiz 14: Chemical Kinetics

The reaction A + 2B → products has been found to have the rate law,rate = k[A][B]².While holding the concentration of A constant,the concentration of B is increased to three times its initial value.By what factor does the rate of reaction increase?

The reaction A + 2B → products was found to follow the rate law: rate = k[A]²[B].Predict by what factor the rate of reaction will increase when the concentration of A is doubled,the concentration of B is tripled,and the temperature remains constant.

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^-5 s^-1.What is the order of the reaction?

For the reaction BrO₃^- + 5Br^- + 6H⁺ → 3Br² + 3H₂O at a particular time,-Δ[BrO₃^-]/Δt = 1.5 × 10^-2 M/s.What is -Δ[Br^-]/Δt at the same instant?

Consider the general reaction 5Br-(aq) + Br O₃-(aq) + 6H+(aq) → 3Br₂(aq) + 3 H₂O(aq) For this reaction,which is equal to Δ[Br2]/Δt?

For the reaction A + 2B → C,which expression is correct?

What is the name given for the study of how fast reactions take place?

For the hypothetical reaction A + 3B → 2C,the rate should be expressed as

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

For the reaction C₆H₁₄(g) → C₆H₆(g) + 4H₂(g) ,ΔP(H₂) /Δt was found to be 2.5 × 10^-2 atm/s, where ΔP(H₂) is the change in pressure of hydrogen.Determine ΔP(C₆H₁₄) /Δt for this reaction at the same time.

What is the rate expression for the production of X,which is a gas,at constant volume?

The rate constant for a reaction is 4.65 L • mol^-1 • s^-1.What is the overall order of the reaction?

Consider the reaction 2NH₃(g) → N₂(g) + 3 H₂ (g) If the rate Δ[H₂]/Δt is 0.030 mol L^-1 • s^-1,what is Δ[N H₃]/Δt?

Which equation best describes the average rate for the reaction shown? A(aq) + B(aq) → C(aq) + D(aq)

For the following reaction,ΔP(C₆H₁₄) /Δt was found to be -6.2 × 10^-3 atm/s. C₆H₁₄(g) → C₆H₆(g) + 4H₂(g) Determine ΔP(H₂) /Δt for this reaction at the same time.

What are possible units for the reaction rate?

The reaction A + 2B → products has the rate law,rate = k[A][B]³.If the concentration of B is doubled while that of A is unchanged,by what factor will the rate of reaction increase?

The reaction A + 2B → products was found to have the rate law,rate = k[A][B]².Predict by what factor the rate of reaction will increase when the concentration of A is doubled and the concentration of B is also doubled.

Which is the correct unit for a first-order rate constant?

For the overall chemical reaction shown below,which one of the following statements can be rightly assumed? 2 H₂S(g) + O₂(g) → 2S(s) + 2H₂O(l)

Quiz 14: Chemical Kinetics

The reaction A + 2B → products has been found to have the rate law,rate = k[A][B]2.While holding the concentration of A constant,the concentration of B is increased to three times its initial value.By what factor does the rate of reaction increase?

The reaction A + 2B → products was found to follow the rate law: rate = k[A]2[B].Predict by what factor the rate of reaction will increase when the concentration of A is doubled,the concentration of B is tripled,and the temperature remains constant.

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 × 10-5 s-1.What is the order of the reaction?

For the reaction BrO3- + 5Br- + 6H+ → 3Br2 + 3H2O at a particular time,-Δ[BrO3-]/Δt = 1.5 × 10-2 M/s.What is -Δ[Br-]/Δt at the same instant?

Consider the general reaction 5Br-(aq) + Br O3-(aq) + 6H+(aq) → 3Br2(aq) + 3 H2O(aq) For this reaction,which is equal to Δ[Br2]/Δt?