How come salt doesn’t turn into bleach on contact with air, since the only thing separating them chemically is a single oxygen atom?
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Oxygen in the air is in the form of O2, two oxygen atoms stuck together to form an oxygen molecule. For one of the oxygen atoms to bind to the salt molecule it would first have to leave the other oxygen atom in the oxygen molecule, effectively breaking up the oxygen molecule.
Breaking up an oxygen atom requires energy, more energy than we get from creating the bleach (hypochlorous acid) molecule.
Radome’s answer is spot on. I just want to add that that’s the same reason diamonds (or even trees) don’t turn into carbon dioxide on contact with air. The oxygen atoms in O2 are already pretty happy, and even though they’d be even happier as CO2 (carbon dioxide), to get there they have to get ripper apart into single O’s first which they really dislike. So there’s a certain threshold of “activation energy” that has to be applied. That’s what happens when you light a fire. The wood doesn’t burn on contact with air – you have to provide the initial energy (a spark or flame) to help split some O2’s and generate single oxygens to react with the carbon.
I think this question is really showing a fundamental mistake in chemistry teaching/understanding. The mistake is that most people tend to think of atoms as parts in machines or components in cakes etc. Like, if I put together a cogwheel and a pedal with two wheels, you get a bike, so adding one more wheel must result on a tricycle, right? Or adding more sugar to a cake will make it sweeter, right? So then why an extra oxygen in water makes it hydrogen peroxide?
So the weird thing in chemistry is that it works entirely different from what our everyday world does. Imagine you take a microwave oven and saw it into halves. And instead of having two half microwaves, boom, it becomes a t-shirt and a bar of soap. You can do it back together, get a soap and a t-shirt, force them together and whoop, it’s a microwave! However if you force the same soap together with a wristwatch, you get a light bulb. Or, let’s say you press together two soap bars and you get a glass jar.
The thing what I want to say is that absolutely no point looking at atoms as spare parts that are hanging around and can just added or removed freely. They don’t contribute to the final product in a simple way as an extra wheel addition would contribute to a tricycle. There are of course rules, that imaginary “soap bar” doesn’t do random stuff, but you have rules how to force the soap bar out of the glass jar, and how to force it into the t-shirt in order to get your microwave. And the rules are described by the chemical reactions.
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