Q: The eighth image compares rate versus reactant concentration for zero, first, and second order reactions. Which rate law corresponds to a straight line with a positive slope passing through the origin?

$$\text{Rate} = k[\mathrm{A}]$$

Question 1

Which of the following best explains why a powdered solid reacts faster than a solid lump of the same substance, as illustrated in the first two images?

Accepted Answer

Powdered solids have a greater surface area exposed to reactants.

Question 2

Based on the third image, what is the effect of increasing the concentration of reactants on the rate of a chemical reaction?

Accepted Answer

It increases the rate by increasing the number of effective collisions.

Question 3

The fourth image shows glow sticks in beakers at different temperatures. What does this experiment demonstrate about reaction rates?

Accepted Answer

Higher temperatures increase the rate of the chemical reaction.

Question 4

In the fifth image, three beakers show different amounts of bubbling. What is the most likely explanation for the differences in reaction rates?

Accepted Answer

The temperature of the solutions is different in each beaker.

Question 5

Refer to the sixth image. What does the comparison between the two reactions over time illustrate?

Accepted Answer

A reaction with a fast rate produces products more quickly than a reaction with a slow rate.

Question 6

The seventh image shows concentration vs. time for the reaction $$\mathrm{H_2$(g) + I_2$(g) \rightarrow 2HI(g)}. $$What does the slope of the tangent to the $$[\mathrm{H_2$}]$$ curve at a given time represent?

Accepted Answer

The instantaneous rate of disappearance of $$\mathrm{H_2$}.$$

Question 7

The eighth image compares rate versus reactant concentration for zero, first, and second order reactions. Which rate law corresponds to a straight line with a positive slope passing through the origin?

Accepted Answer

$$	ext{Rate} = k[\mathrm{A}]$$

Question 8

The ninth image shows reactant concentration versus time for zero, first, and second order reactions. Which statement is correct about the half-life of a first-order reaction?

Accepted Answer

The half-life is constant and independent of concentration.

Question 9

The tenth and eleventh images show the decomposition of $$\mathrm{N_2O} on a $$platinum surface. Why does increasing the concentration of $$\mathrm{N_2O}$$ not increase the reaction rate after a certain point?

Accepted Answer

The reaction is limited by the surface area of platinum, not by $$\mathrm{N_2O}$$ concentration.

Question 10

The twelfth image shows a straight-line plot of $$\ln[\mathrm{A}]$$ versus time. What is the order of the reaction, and what does the slope represent?

Accepted Answer

First order; slope = $$-k$$

Question 11

The thirteenth image shows a straight-line plot of $$[\mathrm{A}]$$ versus time. What is the order of the reaction, and what does the slope represent?

Accepted Answer

Zero order; slope = $$-k$$

Question 12

The sixteenth and seventeenth images show plots of $$\ln[\mathrm{NO_2$}]$$ and $$1/[\mathrm{NO_2$}]$$ versus time. If the plot of $$1/[\mathrm{NO_2$}]$$ versus time is linear, what is the order of the reaction?

Accepted Answer

Second order

Question 13

The eighteenth image summarizes rate laws. Which of the following is true for a second-order reaction?

Accepted Answer

The units of the rate constant are $$\mathrm{M$$^{-1}$$ s$$^{-1}$$}.$$

Question 14

The nineteenth image shows the effect of temperature on the fraction of collisions with sufficient energy. According to collision theory, why does increasing temperature increase reaction rate?

Accepted Answer

It increases the fraction of molecules with energy greater than $$E_a.$$

Question 15

The twentieth image shows a reaction energy profile. What does the peak of the curve represent?

Accepted Answer

The activation energy barrier (transition state).

Question 16

The twenty-second image shows an Arrhenius plot. What is the relationship between the slope of the line and the activation energy?

Accepted Answer

Slope = $$-E_a/R$$

Question 17

The twenty-third image shows an energy diagram for a two-step mechanism. Which step determines the overall reaction rate?

Accepted Answer

The step with the highest activation energy.

Question 18

The twenty-fourth image compares catalyzed and uncatalyzed reaction pathways. What is the effect of a catalyst on the reaction?

Accepted Answer

It decreases the activation energy, providing an alternative pathway.

Question 19

The last image shows an enzyme-substrate complex. What is the role of the enzyme in this process?

Accepted Answer

It lowers the activation energy for the reaction.

Chemical Kinetics: Principles, Rate Laws, and Mechanisms

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