Video Transcript
Which of the following chemical
reactions shows the formation of ozone? (A) O3 gas forms O2 gas plus O
gas. (B) O2 gas forms two O gas. (C) Two O gas forms O2 gas. (D) O gas plus O2 gas forms O3
gas. Or (E) Two O gas plus O2 gas forms
two O3 gas.
In this question, we need to
identify which chemical equation describes the formation of ozone.
Ozone is an unusual compound
because it is a triatomic molecule but only contains the element oxygen. It is much less stable than
diatomic oxygen with the chemical formula O2. Ozone is detrimental to human
health if it is at sea level because it is a powerful oxidant and can damage mucous
and respiratory tissues. It is, however, beneficial for
human health if it is in the stratosphere because it protects us from harmful UV
radiation.
Ozone tends to form in the
stratosphere as high-energy UV radiation from the Sun splits an oxygen molecule into
two individual oxygen atoms. The equation shows how a
high-energy light photon makes two oxygen atoms from one O2 molecule in the
stratosphere. The two oxygen atoms are highly
reactive, and they can combine with diatomic oxygen molecules and produce triatomic
ozone molecules.
The figure shows how a single
high-energy UV photon can generate two oxygen atoms and two ozone molecules. We should appreciate that intense
UV radiation continuously bombards the Earth, so this ozone production reaction
occurs all the time and makes millions of tons of ozone every day. The second chemical equation shows
how one oxygen atom combines with diatomic oxygen and makes the ozone compound.
So we now know how ozone is formed,
and we know that ozone has the formula O3. So in the formation of ozone, O3
will be one of the products. Thus, the answer must be option (D)
or (E). The equation for option (E) doesn’t
balance, so option (E) is incorrect and option (D) must be correct.
We can confirm this with this third
chemical equation. It describes how the generated
ozone molecules effectively protect us from harmful radiation. It shows that ozone molecules split
into diatomic oxygen and an oxygen atom as they absorb otherwise damaging light
energy. This equation shows the splitting
of ozone. The formation of ozone is the
reverse equation. Thus, the chemical equation that
shows the formation of ozone is (D): O gas plus O2 gas forms O3 gas.
