Question Video: Chemical Equation of Decomposing Oxygen Molecule by Ultraviolet Light Chemistry

In the atmosphere, ultraviolet light can decompose molecules of oxygen gas into individual atoms of oxygen. What is the chemical equation for this reaction?

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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.

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