Chemistry, asked by abbasihussnain597, 9 months ago

Molecules such as CFCs (chlorofluorocarbons) generate free radicals which destroy atmospheric ozone. State the nature of the ozone-destroying free radicals, and write equations to help you to explain how these radicals destroy ozone?

Answers

Answered by prachisharma3206
1

Answer:

Chlorofluorocarbons and Ozone Depletion

At the University of California, Irvine, F. Sherwood Rowland and Mario J. Molina discovered that

chlorofluorocarbons (CFCs) could deplete Earth’s atmospheric ozone layer, which blocks the sun’s

damaging ultraviolet rays. When the scientists reported their findings in 1974, CFCs were in wide

use in refrigeration, air conditioning and aerosol spray cans. The research set off fierce debates,

yet the work of Rowland and Molina convinced skeptical industrialists, policymakers and the public

of the danger of CFCs.

The scientists’ advocacy — and the discovery by other researchers that the ozone layer over the

Antarctic was thinning — led to worldwide phaseout of CFCs and the development of safer

alternatives. For their work, Rowland and Molina shared the 1995 Nobel Prize in Chemistry with

another atmospheric chemist, Paul J. Crutzen.

Widespread Use of CFCs

In the 1920s, refrigeration and air

conditioning systems used

compounds such as ammonia,

chloromethane, propane and

sulfur dioxide as refrigerants.

Though effective, the compounds

were toxic and flammable, and

exposure to them could result in

serious injury or death. In the

1930s, chemists at Frigidaire led

by Thomas Midgely Jr. worked to

develop nontoxic, nonflammable

alternatives to the refrigerants.

The team focused their effort on

compounds containing carbon

along with halogens such as

fluorine and chlorine. Such

compounds were known to be

volatile and chemically inert,

desirable properties for their use

in refrigeration.

The first compound they

developed was dichlorodifluoro-

methane, which they dubbed

“Freon.” By the early 1970s,

CFCs were in widespread use,

and worldwide production of the

compounds had reached nearly

one million tons per year.

The Importance of Ozone

Ozone, a molecule made up of

three oxygen atoms, is a

confusing molecule from an

environmental standpoint. In the

troposphere, the region of the

atmosphere from Earth’s surface

up to about 6 miles, ozone is a

pollutant that is a component of

smog.

But in the stratosphere,

the region of the

atmosphere from 6 to 31

miles, ozone absorbs the

sun’s potentially

damaging ultraviolet (UV)

radiation. Without this

protective ozone layer in

the atmosphere, animals

and plants wouldn’t

survive on land.

Rowland’s interest in the

fate of CFCs in the

atmosphere was sparked

by a talk he heard at a

conference in 1972. The

speaker discussed a

British scientist’s findings

that practically all of a

particular CFC ever made

was still present in the

atmosphere.

Rowland, a chemistry professor,

decided to study the fate of CFCs

in the atmosphere. Although

CFCs are inert in the lower

troposphere, Rowland realized

that they can be broken down by

UV radiation once they drift up

into the stratosphere.

Courtesy UC

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