chlorine and Bromine Halogen Cycles

What is a halogen cycle

A catalytic ozone-destruction cycle involving halogen radicals such as chlorine or bromine.

What is the ClOₓ cycle

A catalytic ozone-destruction cycle involving chlorine and chlorine monoxide radicals.

What is the primary natural source of atmospheric chlorine mentioned in the lecture

Methyl chloride (CH₃Cl).

How is chlorine released from methyl chloride

UV-C photolysis breaks CH₃Cl apart, releasing a chlorine radical.

What is the photolysis reaction of methyl chloride

CH₃Cl + hν → CH₃• + Cl•.

Why is atomic chlorine important in the stratosphere

It is highly reactive toward ozone and can catalytically destroy it.

How does chlorine destroy ozone through Mechanism I

Cl• + O₃ → ClO• + O₂, followed by ClO• + O → Cl• + O₂.

What is the net reaction of the chlorine Mechanism I cycle

O₃ + O → 2O₂.

What is the BrOₓ cycle

A catalytic ozone-destruction cycle involving bromine and bromine monoxide radicals.

What is the primary natural source of bromine mentioned in the lecture

Methyl bromide (CH₃Br).

How is bromine released from methyl bromide

UV-C photolysis breaks CH₃Br apart, releasing a bromine radical.

What is the photolysis reaction of methyl bromide

CH₃Br + hν → CH₃• + Br•.

How does bromine destroy ozone through Mechanism I

Br• + O₃ → BrO• + O₂, followed by BrO• + O → Br• + O₂.

What is the net reaction of the bromine Mechanism I cycle

O₃ + O → 2O₂.