If an average \(\mathrm{O}_{3}\) molecule "lives" only \(100-200\) seconds in the stratosphere before undergoing dissociation, how can \(\mathrm{O}_{3}\) offer any protection from ultraviolet radiation?

Ozone is formed in the stratosphere as a result of the interactions between oxygen molecules (O2) and ultraviolet (UV) radiation from the Sun. When high-energy UV-C radiation (100-280 nm) encounters O2, it causes the O2 molecule to dissociate into two separate oxygen atoms (O). These oxygen atoms can then react with other O2 molecules to form ozone (O3). This process can be represented by the following equations: 1. \(O_2 + UV-C \rightarrow 2O\) 2. \(O + O_2 \rightarrow O_3\) Ozone can also dissociate back into oxygen molecules and atoms when it absorbs UV-C or UV-B radiation (280-320 nm), as shown in the following reaction: 3. \(O_3 + UV-C / UV-B \rightarrow O_2 + O\)

Ozone in the stratosphere is crucial for life on Earth, as it plays a major role in protecting living organisms from the harmful effects of ultraviolet radiation. The absorption of UV-C and UV-B radiation by ozone effectively filters out most of these dangerous wavelengths from reaching the Earth's surface. When an ozone molecule absorbs UV-C or UV-B radiation, it undergoes dissociation, as described in reaction 3 above. This process not only helps reduce the amount of harmful UV radiation that reaches the Earth, but also releases an oxygen atom, which can then go on to react with other O2 molecules to create more O3, thus maintaining the ozone layer.

While it's true that individual ozone molecules have a relatively short lifetime in the stratosphere (100-200 seconds), this does not imply that the ozone layer as a whole is ineffective in providing protection from UV radiation. The continuous formation and dissociation of ozone occur simultaneously in the stratosphere. While individual ozone molecules may have a short lifetime, new ozone molecules are constantly being formed as a result of reactions between oxygen atoms and O2 molecules, enabled by the absorption of UV-C radiation. This ongoing process ensures that the ozone layer remains sufficiently dense to absorb and filter out harmful UV radiation, providing crucial protection for life on Earth. In summary, even though individual ozone molecules have short lifetimes, the ozone layer as a whole continues to serve as an effective shield against harmful ultraviolet radiation. The ongoing formation and dissociation of ozone molecules in the stratosphere ensures that the ozone layer remains intact and able to protect living organisms from the damaging effects of UV radiation.