Video Transcript
In the atmosphere, ultraviolet
light can decompose molecules of oxygen gas into individual atoms of oxygen. What is the chemical equation for
this reaction?
In the reaction described in this
question, ultraviolet light is causing oxygen gas, which has the chemical formula
O2, to decompose into individual atoms of oxygen. So, if we start off with one
molecule of oxygen gas, it would decompose into two atoms of oxygen. To complete our chemical equation,
we shouldn’t forget to write light over the reaction arrow since this reaction
requires UV light in order to start, which makes this particular reaction a
photochemical reaction. This reaction described is the
first step in the reaction of ozone formation in Earth’s atmosphere.
The next step of the reaction
involves each of those individual atoms of oxygen that are produced striking another
molecule of oxygen gas, which would each form a molecule of ozone or O3. This photochemical reaction
initiated by UV light striking oxygen in the atmosphere is extremely important for
life on Earth, as ozone shields us from the harmful effects of UV radiation. But this question was only asking
us about the first step in this process, which is where UV light causes O2 gas to
decompose into two oxygen atoms.
