Unit 5 Kinetics MC Practice

If 87.5 percent of a sample of pure ¹³¹I decays in 24 days, what is the half-life of ¹³¹I?

• 6 days

• 8 days

• 12 days

• 14 days

• 21 days

Tags

NGSS.HS-PS1-8

The graph above shows the results of a study of the reaction of X with a large excess of Y to yield Z. The concentrations of X and Y were measured over a period of time. According to the results, which of the following can be concluded about the rate law for the reaction under the conditions studied?

• It is zero order in [X].

• It is first order in [X].

• It is second order in [X].

• It is first order in [Y].

• The overall order of the reaction is 2.

Tags

NGSS.HS-PS1-5

Which of the following rate expressions agrees best with this possible mechanism?

• rate = k [NO]²

• rate = k[NO]/[O₂]

• rate = k[NO]²/[O₂]

• rate = k[NO]²[O₂]

• rate = k[N₂O₂][O₂]

Tags

NGSS.HS-PS1-5

The rate of a certain chemical reaction between substances M and N obeys the rate law above. The reaction is first studied with [M] and [N] each 1 x 10^-3 molar. If a new experiment is conducted with [M] and [N] each 2 x 10^-3 molar, the reaction rate will increase by a factor of

• 2

• 4

• 6

• 8

• 10

Tags

NGSS.HS-PS1-5

Gaseous cyclobutene undergoes a first-order reaction to form gaseous butadiene. At a particular temperature, the partial pressure of cyclobutene in the reaction vessel drops to one-eight it original value in 124 seconds. What is the half-life for this reaction at this temperature?

• 15.5 sec

• 31.0 sec

• 41.3 sec

• 62.0 sec

• 124 sec

Tags

NGSS.HS-PS1-5

Factors that affect the rate of a chemical reaction include which of the following?

• II only

• I and II only

• I and III only

• II and III only

• I, II, and III

Tags

NGSS.HS-PS1-5

Which of the following statements best explains why an increase in temperature of 5-10 Celsius degrees can substantially increase the rate of a chemical reaction?

• The activation energy for the reaction is lowered.

• The number of effective collisions between reactant particles is increased.

• The rate of the reverse reaction is increased.

• ΔH for the reaction is lowered.

• ΔG for the reaction becomes more positive.

Tags

NGSS.HS-PS1-5

A reaction mechanism for the destruction of ozone, O₃ (g), is represented above. In the overall reaction, NO(g) is best described as

• an inhibitor

• a catalyst

• a reactant

• an intermediate

• a product

Tags

NGSS.HS-PS1-2

The rate law for the reaction of nitrogen dioxide and chlorine is found to be rate = k[NO₂]²[Cl₂]. By what factor does the rate of the reaction change the concentrations of both NO₂ and Cl₂ are doubled?

• 2

• 3

• 4

• 6

• 8

Tags

NGSS.HS-PS1-5

A kinetics experiment is set up to collect the gas that is generated when a sample of chalk, consisting primarily of solid CaCO₃ , is added to a solution of ethanoic acid, CH₃COOH. The rate of reaction between CaCO₃ and CH₃COOH is determined by measuring the volume of gas generated at 25^oC and 1 atm as a function of time. Which of the following experimental conditions is most likely to increase the rate of gas production?

• Decreasing the volume of ethanoic acid solution used in the experiment.

• Decreasing the concentration of ethanoic acid solution used in the experiment.

• Decreasing the temperature at which the experiment is performed.

• Decreasing the particle size of the CaCO₃ by grinding it into a fine powder.

Tags

NGSS.HS-PS1-5