AP Chemistry Unit 5

Which step of a reaction mechanism determines the rate?

• the slow step

• the fast step

• the first step

• the second step

Answer explanation

The slow step of a reaction mechanism determines the rate because it is the step with the highest activation energy, leading to the overall rate of the reaction.

Tags

NGSS.HS-PS1-5

How does a catalyst speed up a reaction?

• Adding more reactant

• Providing a pathway that has a lower activation energy

• Increasing the activation energy

• Increasing binding energy

Answer explanation

A catalyst speeds up a reaction by providing a pathway with a lower activation energy, making it easier for the reaction to occur.

Tags

NGSS.HS-PS1-4

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

Match the following properties with their classification as either an intensive or extensive property.

• Appearance of an object

• Melting point

• Color of an object

• Metallic

• Temperature at which an object changes from solid to liquid

• Silver

• Amount of matter in an object

• Mass

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

NGSS.HS-PS3-1

What is the potential energy of the products?

• 100 kJ

• 250 kJ

• 50 kJ

• 200 kJ

Answer explanation

The potential energy of the products is 100 kJ, as indicated in the correct answer choice.

Tags

NGSS.HS-PS1-4

What is the name of k that appears in the equation used to calculate the rate of a chemical reaction?

• Reaction Rate

• Rate Equation

• Rate Law

• Rate Constant

Answer explanation

The name of k that appears in the equation used to calculate the rate of a chemical reaction is Rate Constant.

Tags

NGSS.HS-PS1-5

The activation energy of the forward reaction is best represented by what number shown on the graph:

• 2

• 4

• 5

• 3

Answer explanation

The activation energy of the forward reaction is best represented by the number 2 on the graph as it corresponds to the peak of the curve, indicating the energy required for the reaction to occur.

Tags

NGSS.HS-PS1-4

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

NGSS.HS-PS1-4

NGSS.HS-PS1-5