1.5 Quiz

For the reaction, 2 H₂S(g) + O₂(g) 2 S(s) + 2 H₂O(l), which one of the following statements is absolutely true?

• The reaction is first order with respect to H₂S and second order with respect to O₂.
• The reaction is fourth order overall.
• The rate law is: rate = k[H₂S]2[O₂].
• The rate law is: rate = k[H₂S][O₂].
• The rate law cannot be determined from the information given.

The first-order reaction A → B, has k = 8.00 s⁻¹. If [A]₀ = 0.500 M, how long will it take [A] = 0.200 M?

• 0.115 s
• 0.244 s.
• 0.100 s
• 0.488 s
• 8.18 s

The first-order reaction A → B, has k = 5.67 s⁻¹. If [A]₀ = 0.500 M, how long will it take [A] = 0.124 M?

• 0.122 s
• 0.244 s
• 0.100 s
• 0.488 s
• 8.18 s

We are studying the following reaction. We make a plot of ln[A] vs. time as the reaction proceeds. This plot turns out to be linear with a slope of -0.25. What is the rate law expression for this reaction? 2 A → 3 B

• rate = 0.25 s⁻¹ [A]
• rate = 0.25 M⁻¹s⁻¹ ln[A]
• rate = 0.25 M⁻¹s⁻¹ [A]²
• rate = -0.25 s⁻¹ [A]
• rate = 0.0625 M⁻¹s⁻¹ [A]²

A reaction is first order in A. If the rate constant of the reaction is 6.00 × 10–3 s⁻¹, what is the half-life (t1/2) of the reaction?

• 4.98 × 10⁻³ s
• 115 s
• 200 s
• 1.73 × 10⁻³ s
• 3.45 × 10⁻³ s

A reaction is first order in A. If the rate constant of the reaction is 3.45 × 10–3 s⁻¹, what is the half-life (t1/2) of the reaction?

• 4.98 × 10⁻³ s
• 100 s
• 201 s
• 1.73 × 10⁻³ s
• 3.45 × 10⁻³ s

The half-life (t1/2) of a first-order reaction is 0.100 s. What is the rate constant?

• 6.93 s⁻¹
• 0.144 s⁻¹
• 0.693 s⁻¹
• 3.01 s⁻¹
• 0.0693 s⁻¹

The half-life (t1/2) of a first-order reaction is 0.950 s. What is the rate constant?

• 6.93 s⁻¹
• 0.144 s⁻¹
• 0.729 s⁻¹
• 3.01 s⁻¹
• 0.0693 s⁻¹

What percentage of a material will persist after 60 minutes if it’s half life is 30 minutes?

• 50%
• 33%
• 25%
• 12.5%
• none of the above

What percentage of a material will persist after 80 minutes if it’s half life is 20 minutes?

• 50%
• 33%
• 25%
• 12.5%
• 6.25%