Free Radicals and Catalytic Ozone Destruction and Catalytic Ozone Destruction: Mechanism I

What is a free radical

A chemical species containing an unpaired electron.

Why are free radicals highly reactive

Their unpaired electrons make them likely to react with other chemical species.

What is catalytic ozone destruction

Ozone destruction through reactions involving a catalyst that is regenerated during the reaction cycle.

What is the general first reaction in catalytic ozone destruction

X• + O₃ → XO• + O₂.

What is the general second reaction in catalytic ozone destruction

XO• + O → X• + O₂.

What is X in catalytic ozone destruction

A free-radical species that participates in ozone-destruction reactions.

What happens to X during a catalytic cycle

It reacts with ozone and is later regenerated.

What is the net reaction for Mechanism I

O₃ + O → 2O₂.

Why is X considered a catalyst

It is regenerated and does not appear in the overall net reaction.

What happens to odd oxygen during catalytic ozone destruction

Its concentration decreases.

Why do catalytic reactions reduce ozone concentrations

They provide additional pathways for ozone destruction beyond the Chapman reactions.

What is catalytic ozone-destruction Mechanism I

A two-step reaction in which a radical reacts with ozone and the resulting radical reacts with atomic oxygen.

What is the first step of Mechanism I

X• + O₃ → XO• + O₂.

What is the second step of Mechanism I

XO• + O → X• + O₂.

What is the net reaction of Mechanism I

O₃ + O → 2O₂.

Is atomic oxygen required for Mechanism I

Yes, atomic oxygen is required in the second reaction.

What happens to the catalyst in Mechanism I

The original radical X• is regenerated.

How does Mechanism I destroy odd oxygen

It converts ozone and atomic oxygen into molecular oxygen.

Which mechanism is responsible for most ozone destruction according to the lecture

Mechanism I.