ShmoopTube

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And here’s your Shmoop du jour, brought to you by oxygen. [Man on a sofa surrounded by oxygen]

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We love it so much we’d die without it.

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…Literally.

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Okay, here’s our question: The disappearance rate of oxygen in the reaction

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3 O2?

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yields 2 O 3 is equal to 0.40 moles per liter per second.

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Approximate the appearance rate of ozone.

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And here are your potential answers…

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All right, so we know the rate at which O2 is disappearing. [Magician makes O2 disappear]

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All we need to do is use the stoichiometry of the reaction equation

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to find the rate of O3 appearance.

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Easy peasy lemon squeezy? [Lemon squeezed on equation]

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Alright, well it's not as scary as it sounds…

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Using the reaction equation, for every 3 oxygen molecules that disappear, 2 ozone molecules

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appear.

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O2 is disappearing at a rate of 0.40 moles per liter per second.

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No, not that kind of mole – the Avogadro’s number kind. [Mole in the ground and Avogadro's constant lands on its head]

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Yeah, it’s confusing.

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Just don't try shoving a mole into a beaker and you should be okay. [Student holding a mole in a beaker]

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Anyway, we can set up a proportion using the stoichiometry and reaction rates to find x,

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which represents the unknown rate of O3 appearance.

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Which is what the question is asking for, in case you got lost over there in the labyrinth [A couple lost in a maze]

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of chemistry and angry moles…

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If we multiply both sides of this equation by 0.4 moles per liter per second and crunch

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the numbers…

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Mm, mm…

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Mathy…

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… We find out that the rate of appearance of ozone is 0.27 moles per liter per second.

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So B is the correct answer.

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Now go take a deep breath and thank a tree for that sweet, sweet O2 . [Girl takes deep breath and hugs a tree]

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Seriously, write it a thank you card.

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No one ever appreciates all the hard work its doing…[Thank you card by a tree]

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