AP Chemistry Exam

Consider the mechanism shown. Which species is a catalyst and which is an intermediate, respectively?

• none, F

• NO₂F, F

• NO₂, NO₂

• none, NO₂F

Answer explanation

In the mechanism shown, there is no catalyst present, making the correct choices none for catalyst and F for intermediate.

Consider the proposed mechanism shown. In the overall reaction, what is the overall reaction?

• IO⁻ + Cl⁻ → ClO⁻ + I⁻

• ClO⁻ + I⁻ → IO⁻ + Cl⁻

• IO⁻ + Cl⁻

• ClO⁻ + I⁻

Answer explanation

The correct overall reaction is ClO^- + I^- -> IO^- + Cl^- as shown in the proposed mechanism.

Tags

NGSS.HS-PS1-2

What is the rate law for the reaction with this slow elementary step? A + 2B --> D + C

• rate = k[A]²

• rate = k[A][B]²

• rate = k[A][B]

• rate = k[A]

Answer explanation

The rate law is determined by the stoichiometry of the slow step, which is rate = k[A][B]^2.

Tags

NGSS.HS-PS1-5

If you quadruple the concentration and the rate quadruples, what order is this reaction?

• zero

• first

• second

Answer explanation

If concentration quadruples and rate quadruples, it is a first-order reaction where rate is directly proportional to concentration.

Tags

NGSS.HS-PS1-5

___________ are produced in one step and used up in a later step and __________________ are present and unchanged in the reactants and the products

• intermediates, catalysts

• catalysts, intermediates

Answer explanation

Intermediates are produced in one step and used up in a later step, while catalysts are present and unchanged in the reactants and the products. Therefore, the correct answer is intermediates, catalysts.

More collisions correspond to a: 

• Faster reaction rate  

• Slower reaction rate

• Constant reaction rate 

• None of the above

Answer explanation

More collisions correspond to a faster reaction rate because a higher frequency of collisions leads to more successful reactions occurring in a given time period.

Tags

NGSS.HS-PS1-5

Is this an endothermic or exothermic reaction?

• endothermic

• exothermic

Answer explanation

The correct choice is 'endothermic' because this reaction absorbs heat from its surroundings, resulting in a decrease in temperature.

Tags

NGSS.HS-PS1-4

The potential energy of the reactants is..?

• 100 kJ

• 250 kJ

• 50 kJ

• 200 kJ

Answer explanation

The correct answer is 50 kJ because the potential energy of the reactants is given as 50 kJ in the answer choices.

Tags

NGSS.HS-PS1-4

Which state of matter will react the SLOWEST?

• solid

• liquid

• gas

• the all react at the same rate

Answer explanation

Solids react the slowest because their particles are tightly packed and have the least amount of energy to react compared to liquids and gases.

What is the rate law for the reaction with this slow elementary step? A --> B + C

• rate = k[A]²

• rate = k[B]²

• rate = k[A][B]

• rate = k[A]

Answer explanation

The rate law for the reaction with the slow elementary step A -> B + C is rate = k[A], as the rate is directly proportional to the concentration of A.

Tags

NGSS.HS-PS1-5