Question 1

A chemist is studying the decomposition of a substance and finds that a plot of $$\ln [A]$$ versus time yields a straight line with a negative slope. What is the order of the reaction with respect to $$A$$?

Accepted Answer

First order

Question 2

The rate law for a reaction is given by $$	ext{Rate} = k[A][B]^2. If $$the concentration of $$B is $$doubled while $$A$$ remains constant, by what factor does the rate increase?

Accepted Answer

4

Question 3

A student measures the absorbance of a solution at a specific wavelength and finds $$A = 0.50. If $$the molar absorptivity $$\epsilon is$$ $$100\ 	ext{L mol}^{-1}	ext{cm}^{-1}$$ and the path length $$l is$$ $$1.0\ 	ext{cm}$$, what is the concentration $$c of $$the solution according to Beer-Lambert Law?

Accepted Answer

$$0.005\ 	ext{mol/L}$$

Question 4

Which of the following best explains why increasing the temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the number of successful collisions by providing more molecules with energy greater than the activation energy.

Question 5

A reaction is found to be first order in $$A$$ and zero order in $$B. $$Which of the following rate laws correctly represents this reaction?

Accepted Answer

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

Question 6

A radioactive isotope decays with a half-life of 5 days. How much of a 100 g sample remains after 15 days?

Accepted Answer

12.5 g

Question 7

Which of the following statements about mass spectrometry is correct?

Accepted Answer

It determines the average atomic mass by analyzing isotopic abundances.

Question 8

In a certain reaction, doubling the concentration of reactant $$A$$ causes the rate to quadruple, while doubling $$B$$ has no effect. What is the most likely rate law?

Accepted Answer

$$	ext{Rate} = k[A]^2$$

Question 9

Which of the following is NOT a necessary condition for a successful collision in a chemical reaction?

Accepted Answer

Reactant molecules must be in the gas phase.

Question 10

A solution of a colored compound is analyzed using a spectrophotometer. If the path length is doubled and the concentration remains the same, what happens to the absorbance according to Beer-Lambert Law?

Accepted Answer

It is doubled.

Question 11

A reaction has a rate constant $$k$$ with units of $$	ext{M}^{-1}	ext{s}^{-1}. $$What is the order of the reaction?

Accepted Answer

Second order

Question 12

Which of the following changes will NOT increase the rate of a chemical reaction?

Accepted Answer

Decreasing the surface area of a solid reactant

Question 13

A first-order reaction has a rate constant $$k = 0.693\ 	ext{day}^{-1}. $$What is the half-life of the reaction?

Accepted Answer

$$1.0\ 	ext{day}$$

Question 14

Which of the following best describes the Beer-Lambert Law?

Accepted Answer

$$A = \epsilon c l$$

Question 15

A reaction is monitored and the following data are collected: $$[A]$$ decreases linearly with time. What is the order of the reaction with respect to $$A$$?

Accepted Answer

Zero order

Question 16

A sample contains two isotopes of an element: 70% isotope X (mass 10.0 amu) and 30% isotope Y (mass 11.0 amu). What is the average atomic mass of the element?

Accepted Answer

10.3 amu

Question 17

Which of the following statements about activation energy is correct?

Accepted Answer

It is the minimum energy required for a reaction to occur.

Question 18

A reaction is carried out in a laboratory and the rate is measured at different concentrations. The following data are obtained: when $$[A] is $$doubled, the rate increases by a factor of 2; when $$[B] is $$doubled, the rate increases by a factor of 4. What is the rate law?

Accepted Answer

$$	ext{Rate} = k[A][B]^2$$

Question 19

Which of the following is a real-world application of the Beer-Lambert Law?

Accepted Answer

Determining the concentration of hemoglobin in blood using a spectrophotometer

Question 20

A reaction has a rate law $$	ext{Rate} = k[A]. If $$the initial concentration of $$A is$$ $$0.10\ 	ext{M}$$ and the rate constant $$k = 0.20\ 	ext{s}^{-1}$$, what is the initial rate?

Accepted Answer

$$0.020\ 	ext{M s}^{-1}$$

Chemical Kinetics, Beer-Lambert Law, and Mass Spectrometry: Study Notes

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