Question 1

Which of the following best describes the reaction rate (v) in a chemical reaction?

Accepted Answer

The speed at which reactants are converted to products, typically expressed as a change in [product] over a time interval.

Question 2

Given the reaction $$A \rightarrow B$$, if $$[A]_0 = 1.0\, \mathrm{M}$$ and $$[A] = 0.8\, \mathrm{M}$$ after $$2$$ seconds, what is the reaction rate $$v$$?

Accepted Answer

$$0.20\, \mathrm{M/s}$$

Question 3

Which of the following units is most appropriate for expressing reaction velocity ($$v$$)?

Accepted Answer

$$\mathrm{mol/L \cdot s}$$

Question 4

In a time plot of a reaction, what does the slope of the line tangent to the curve at any point represent?

Accepted Answer

The reaction rate ($$v) at $$that specific time

Question 5

A reaction $$A \rightarrow B$$ starts with $$[A]_0 = 1.4\, \mathrm{M}$$ and after $$4.4$$ seconds, $$[A] = 1.1\, \mathrm{M}. $$What is the reaction rate $$v$$?

Accepted Answer

$$0.068\, \mathrm{M/s}$$

Question 6

Which of the following statements about enzyme-catalyzed reactions is correct?

Accepted Answer

The reaction rate typically decreases over time.

Question 7

If the concentration of a reactant decreases from $$2.0\, \mathrm{M} to$$ $$1.6\, \mathrm{M} in$$ $$4$$ seconds, what is the average reaction rate?

Accepted Answer

$$0.10\, \mathrm{M/s}$$

Question 8

Which equation correctly represents the calculation of reaction rate for $$A \rightarrow B$$?

Accepted Answer

$$v = -\dfrac{\Delta [A]}{\Delta t}$$

Question 9

A student measures the concentration of $$A in a $$reaction $$A \rightarrow B at $$several time points and plots $$[A] vs. $$time. What does the steepest negative slope on the graph indicate?

Accepted Answer

The fastest rate of product formation

Question 10

Why is the reaction rate often negative when calculated using $$\Delta [A]/\Delta t$$ for a reactant?

Accepted Answer

Because the concentration of $$A$$ decreases over time

Question 11

In a practical laboratory scenario, why is it important to use the tangent to the curve rather than the average slope when determining the instantaneous reaction rate?

Accepted Answer

Because the tangent gives the rate at a specific moment, reflecting real-time changes in concentration.

Question 12

A reaction $$A \rightarrow B is $$monitored, and the following data are collected: $$[A]_0 = 2.0\, \mathrm{M}$$, $$[A] = 1.7\, \mathrm{M}$$ after $$1.5$$ seconds. What is the reaction rate $$v$$?

Accepted Answer

$$0.20\, \mathrm{M/s}$$

Question 13

Which of the following best explains why reaction rates are typically measured at the beginning of a reaction?

Accepted Answer

Because the concentration of reactants is highest and the rate is most consistent.

Question 14

If a reaction's rate is measured as $$0.25\, \mathrm{M/s}$$, what does this value represent?

Accepted Answer

The amount of reactant consumed per second per liter.

Question 15

A biochemist observes that the reaction rate of an enzyme-catalyzed reaction decreases over time. Which is the most likely explanation?

Accepted Answer

The substrate concentration is decreasing.

Reaction Rate in Biochemistry: Concepts and Calculations

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