Question 1

The image shows two test tubes containing the same chemical reaction, but with different forms of a solid reactant (powdered on the left, chunk on the right). Based on chemical kinetics, which statement best explains why the reaction in the left test tube proceeds faster?

Accepted Answer

The powdered solid has a larger surface area, increasing the frequency of collisions between reactant particles.

Question 2

If the reaction in both test tubes is the decomposition of calcium carbonate ($$\mathrm{$$CaCO_3$$}) $$with hydrochloric acid ($$\mathrm{HCl}$$), which factor is primarily responsible for the difference in reaction rates observed?

Accepted Answer

Physical state (surface area) of the calcium carbonate.

Question 3

Suppose the reaction in the left test tube is completed in 2 minutes, while the right test tube takes 6 minutes. If both reactions are described by the rate law $$\mathrm{Rate = k[$$CaCO_3$$][HCl]}$$, what is the most likely reason for the difference in reaction times?

Accepted Answer

The powdered form provides more surface area, increasing the effective concentration of $$\mathrm{$$CaCO_3$$} at $$the interface.

Question 4

Which of the following changes would NOT increase the rate of reaction in the test tubes shown?

Accepted Answer

Decreasing the temperature of the reaction mixture.

Question 5

If the reaction in the left test tube is zero order with respect to $$\mathrm{$$CaCO_3$$}$$, what would happen to the rate if the amount of powdered $$\mathrm{$$CaCO_3$$} is $$doubled?

Accepted Answer

The rate would remain unchanged.

Question 6

A student claims that the reaction in the right test tube (chunk) is slower because the rate constant $$k is $$smaller. Is this claim correct? Why or why not?

Accepted Answer

No, the rate constant $$k is $$independent of the physical state of the reactant; the slower rate is due to decreased surface area.

Question 7

If both test tubes are placed in a hot water bath, what will happen to the rate of reaction in each tube?

Accepted Answer

The rate of reaction will increase in both tubes due to increased temperature.

Question 8

Which of the following best describes why powdered solids react faster than large chunks in chemical reactions?

Accepted Answer

Powdered solids have a greater surface area, allowing more collisions between reactant particles per unit time.

Question 9

If a catalyst is added to both test tubes, what will be the effect on the rate of reaction?

Accepted Answer

The rate of reaction will increase in both test tubes, but the powdered solid will still react faster.

Question 10

Which of the following statements about the rate constant $$k is $$TRUE for the reactions shown in the test tubes?

Accepted Answer

The value of $$k is $$the same for both reactions if temperature and catalyst are constant.

Chemical Kinetics: Reaction Rates and Rate Laws

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