AP Chem Unit 5 Review

Which of the following gives the correct rate law for the decomposition of hydrogen peroxide?

H₂O₂ -> H₂ + O₂.

• Rate = k [H₂O₂]

• Rate = k [H₂][O₂]

Tags

NGSS.HS-PS1-5

Which of the following explains how a catalyst works?

• It leads to the formation of a more stable activated complex

• If lowers the activation energy of the reaction

• It increases the frequency of collisions

• It improves the orientation of particles

Answer explanation

Be careful. You may have learned in Chem 1 that a catalyst functions by lowering the activation energy of a reaction. That's not entirely true. A catalyst works by improving the reaction conditions and creating a new reaction mechanism.

Which of the following are not included in rate law expressions? (Select all that apply).

• Solids

• Liquids

• Gases

• Intermediates

• Reactants

Tags

NGSS.HS-PS1-5

What two conditions must be met for a reaction to occur?

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Tags

NGSS.HS-PS1-5

Which of the following points represents intermediates in a multistep reaction?

Answer explanation

Points C and E represent the intermediates of this reaction.

Tags

NGSS.HS-PS1-4

Draw an arrow indicating the activation energy (E_a) of this reaction.

Answer explanation

The activation energy will be the distance from the reactants to the highest peak (D). This will be the slow or rate-determining step of this multistep reaction.

Tags

NGSS.HS-PS1-4

If the rate law expression is given as rate = k[NO₂]²[Br₂], what is the overall order of this reaction?

• 0

• 1

• 2

• 3

Answer explanation

If given a rate law expression, the overall order of the reaction is found by adding the exponents. This reaction is second order, in respect to [NO₂], and first order, in respect to [Br₂]. The overall order is 2 + 1 = 3