Q: For the reaction $$BF_3(g$$) + $$NH_3(g$$) \rightarrow F_3BNH_3(g)$$, the rate law is $$\text{Rate} = k[$$BF_3$$][$$NH_3$$]$$. If the instantaneous rate is 0.1065$$\ \text{M/s}$$, $$[$$BF_3$$] = 0.250\ \text{M}$$, and $$[$$NH_3$$] = 0.125\ \text{M}$$, what is the value of k$?

$$3.41\ \text{M}^{-1}\text{s}^{-1}$$

Q: A reaction is found to be first order in $$NO$$ and second order in $$O_2. $$What is the correct rate law for this reaction?

$$\text{Rate} = k[NO][O_2$]^2$$

Question 1

Which of the following statements best describes the difference between the initial rate and the average rate of a chemical reaction?

Accepted Answer

The initial rate is measured at the very beginning of the reaction, while the average rate is calculated over a period of time.

Question 2

For the reaction $$2N_2O_5 ightarrow 4NO_2 + O_2$, if the rate of disappearance of N_2O_5$ is 0.23$$\ 	ext{mol/L\cdot s}$$, what is the rate of appearance of NO_2$?

Accepted Answer

$$0.92\ 	ext{mol/L\cdot s}$$

Question 3

Given the rate law $$	ext{Rate} = k[A]^2[B]$$, what is the overall order of the reaction?

Accepted Answer

3rd order

Question 4

If a reaction is zero order with respect to reactant $$A$$, which of the following graphs best represents the concentration of $$A$$ versus time?

Accepted Answer

A straight line with a constant negative slope

Question 5

For a first-order reaction, if the concentration of reactant $$A is $$halved, what happens to the rate?

Accepted Answer

The rate is halved

Question 6

A reaction has the rate law $$	ext{Rate} = k[A][B]^2. If$$ $$[A] is $$doubled and $$[B] is $$tripled, by what factor does the rate increase?

Accepted Answer

18

Question 7

Which of the following factors does NOT affect the rate constant $$k$$ for a reaction?

Accepted Answer

Concentration of reactants

Question 8

For the reaction $$BF_3(g$$) + $$NH_3(g$$) ightarrow F_3BNH_3(g)$$, the rate law is $$	ext{Rate} = k[$$BF_3$$][$$NH_3$$]$$. If the instantaneous rate is 0.1065$$\ 	ext{M/s}$$, $$[$$BF_3$$] = 0.250\ 	ext{M}$$, and $$[$$NH_3$$] = 0.125\ 	ext{M}$$, what is the value of k$?

Accepted Answer

$$3.41\ 	ext{M}^{-1}	ext{s}^{-1}$$

Question 9

Which statement about the transition state in a chemical reaction is correct?

Accepted Answer

The transition state is higher in energy than both reactants and products.

Question 10

For a reaction with the rate law $$	ext{Rate} = k[A]^0$$, which of the following is true?

Accepted Answer

The rate is independent of $$[A].$$

Question 11

A reaction is found to be first order in $$NO$$ and second order in $$O_2. $$What is the correct rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[NO][O_2$]^2$$

Question 12

If the rate of disappearance of $$A in $$the reaction $$aA + bB \rightarrow cC + dD is$$ $$-\frac{1}{a}\frac{\Delta [A]}{\Delta t}$$, what is the rate of appearance of $$C$$?

Accepted Answer

$$\frac{1}{c}\frac{\Delta [C]}{\Delta t}$$

Question 13

Which of the following best explains why the rate of a zero-order reaction does not change as the concentration of reactant decreases?

Accepted Answer

The rate is independent of reactant concentration.

Question 14

For a second-order reaction, if the concentration of $$A is $$tripled, by what factor does the rate increase?

Accepted Answer

9

Question 15

Which of the following is true about the units of the rate constant $$k$$ for a second-order reaction?

Accepted Answer

$$	ext{M}^{-1}	ext{s}^{-1}$$

Question 16

Which experimental approach is used to determine the order of a reactant in a rate law?

Accepted Answer

Vary the concentration of the reactant and measure the change in rate.

Question 17

If a reaction is first order in $$A$$ and zero order in $$B$$, what will happen to the rate if $$[A] is $$doubled and $$[B] is $$tripled?

Accepted Answer

The rate will double.

Question 18

Which of the following best describes a catalyst in a chemical reaction?

Accepted Answer

It increases the rate of reaction by lowering the activation energy.

Question 19

For the reaction $$2NO + O_2$ ightarrow 2NO_2$$, the rate law is $$	ext{Rate} = k[NO]^x[O_2$]^y. If $$doubling $$[NO]$$ increases the rate by a factor of 4 and doubling $$[O_2$]$$ doubles the rate, what are the values of $$x$$ and $$y$$?

Accepted Answer

$$x = 2,\ y = 1$$

Chemical Kinetics: Reaction Rates, Rate Laws, and Reaction Orders

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