Chemical Reaction Mechanisms

Chemistry ⇒ Chemical Reactions and Equations

Chemical Reaction Mechanisms starts at 11 and continues till grade 12. QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Chemical Reaction Mechanisms. How you perform is determined by your score and the time you take. When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.

See sample questions for grade 12

A reaction mechanism consists of the following steps: Step 1: NO₂ + F₂ → NO₂F + F (slow); Step 2: NO₂ + F → NO₂F (fast). Identify the intermediate.

Define the term 'intermediate' in the context of a reaction mechanism.

Describe how experimental rate laws help in proposing a reaction mechanism.

Describe the difference between a reaction intermediate and a catalyst.

A reaction mechanism consists of the following steps: Step 1: NO₂ + F₂ → NO₂F + F (slow); Step 2: NO₂ + F → NO₂F (fast). Identify the intermediate.

Given the following mechanism: Step 1: 2A → B + C (slow); Step 2: B + D → E (fast). What is the molecularity of the first step?

Given the following mechanism: Step 1: A + B → C (slow); Step 2: C + D → E (fast). What is the rate law for the overall reaction?

In the reaction mechanism: Step 1: Cl₂ → 2Cl (fast); Step 2: Cl + CH₄ → HCl + CH₃ (slow); Step 3: CH₃ + Cl₂ → CH₃Cl + Cl (fast). What is the catalyst, if any?

The rate law for a reaction is found to be rate = k[A][B]. Which of the following mechanisms is consistent with this rate law? (1) A single-step reaction involving A and B, (2) A two-step reaction where the first step involves only A, (3) A two-step reaction where the first step involves A and B, (4) A two-step reaction where the second step involves A and B

Which of the following best describes a catalyst in a reaction mechanism? (1) It is consumed and not regenerated, (2) It appears in the rate law, (3) It is present at the start and regenerated at the end, (4) It increases the activation energy.

Which of the following best describes an elementary step in a reaction mechanism? (1) A single molecular event, (2) The overall reaction, (3) The slowest step, (4) The fastest step

Which of the following is a correct statement about the overall reaction and its mechanism? (1) The mechanism always has fewer steps than the overall reaction, (2) The mechanism may involve species not present in the overall reaction, (3) The mechanism is always a single step, (4) The mechanism does not affect the rate law.

Fill in the blank: A reaction mechanism is considered valid if it is consistent with both the ________ and the observed rate law.

Fill in the blank: In a reaction mechanism, a species that is produced in one step and consumed in a later step is called an ________.

Fill in the blank: The ________ of a reaction mechanism is the number of molecules involved in an elementary step.

Fill in the blank: The ________ of a reaction mechanism is the sequence of elementary steps by which the overall chemical change occurs.

True or False: A catalyst changes the mechanism of a reaction by providing an alternative pathway with lower activation energy.

True or False: An intermediate is present at the beginning and end of a chemical reaction.

True or False: The overall rate law for a reaction can always be deduced from the stoichiometry of the overall reaction.

True or False: The presence of a catalyst changes the enthalpy change (ΔH) of a reaction.