Question 1

Which of the following best explains why a fine powder of a solid reacts faster than a large chunk of the same substance in a heterogeneous reaction?

Accepted Answer

The fine powder has a greater surface area, allowing more collisions between reactant particles.

Question 2

A reaction is found to have the rate law $$	ext{Rate} = k[	ext{A}]^2[	ext{B}]. $$What is the overall order of the reaction?

Accepted Answer

Third order

Question 3

For a first-order reaction, which of the following plots will yield a straight line?

Accepted Answer

$$\ln [A] vs$$. $$t$$

Question 4

The half-life of a first-order reaction is 10 minutes. If the initial concentration of the reactant is 0.80 M, what will the concentration be after 30 minutes?

Accepted Answer

0.20 M

Question 5

Which of the following statements about catalysts is TRUE?

Accepted Answer

Catalysts provide an alternative reaction pathway with a lower activation energy.

Question 6

A reaction has the rate law $$	ext{Rate} = k[	ext{NO}_2]^2. $$Which of the following mechanisms is most consistent with this rate law?

Accepted Answer

A slow step involving two NO$$_2$$ molecules colliding.

Question 7

Which of the following best describes the effect of increasing temperature on the rate constant $$k$$ for a chemical reaction?

Accepted Answer

The rate constant increases exponentially with temperature.

Question 8

The Arrhenius equation is $$k = Ae$$^{-E_a/RT}$$. What does E_a$ represent?

Accepted Answer

The minimum energy required for a reaction to occur.

Question 9

Which of the following is a correct statement about the molecularity of an elementary reaction?

Accepted Answer

Bimolecular reactions involve the collision of two molecules.

Question 10

A gas sample has a mass of 4.00 g and occupies 22.4 L at 0°C and 1 atm. What is the molar mass of the gas?

Accepted Answer

4.00 g/mol

Question 11

Which of the following equations correctly expresses Boyle’s Law?

Accepted Answer

$$P_1V_1 = P_2V_2$$

Question 12

A 2.0 L container holds 1.0 mol of O$$_2$$ gas at 300 K. What is the pressure inside the container? (Use $$R = 0.0821 L$$·atm·mol$$^{-1}$$·K$$^{-1})$$

Accepted Answer

12.3 atm

Question 13

Which of the following best describes the behavior of real gases compared to ideal gases at high pressure and low temperature?

Accepted Answer

Real gases deviate from ideal behavior due to intermolecular forces and finite molecular volume.

Question 14

According to Graham’s Law, which gas will effuse faster: hydrogen (H$$_2) or $$oxygen (O$$_2$$)?

Accepted Answer

Hydrogen, because it is lighter.

Question 15

Which of the following is the correct expression for the density of a gas using the ideal gas law?

Accepted Answer

$$d = \frac{MP}{RT}$$

Question 16

A mixture of gases contains 2 mol of N$$_2$$ and 3 mol of O$$_2. $$What is the mole fraction of O$$_2 in $$the mixture?

Accepted Answer

0.60

Question 17

Which of the following is NOT an assumption of the kinetic-molecular theory of gases?

Accepted Answer

There are strong attractive forces between gas molecules.

Question 18

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

Accepted Answer

A greater fraction of molecules have energy greater than the activation energy.

Question 19

Which of the following is the correct form of the van der Waals equation for real gases?

Accepted Answer

$$\left(P + \frac{n^2$a}{V^2$}\right)(V - nb) = nRT$$

Chemical Kinetics and Gases: Core Concepts and Applications

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