Reactivity of O2 and O3 (1 Viewer)

[HeroicPandas]

When comparing the reactivity of oxygen and ozone, do i compare BOND ENERGIES?

 

[Menomaths]

Yeah, oxygen is very stable as considerable energy is required to break its double bond (which has a high bond energy). The single coordinate covalent bond in ozone requires much less energy to be broken, so ozone readily decomposes to a stable O2 molecule.

 

[HeroicPandas]

thanks

 

[someth1ng]

I would say that it's incorrect to say that the coordinate covalent bond is easier to break because it isn't clear when you say that.

In fact, it's impossible to distinguish between which bond is the double and single bond because there is resonance between the bonds.

What actually occurs is that both of those bonds are EXACTLY the same - the actual molecule would be the AVERAGE of both of those molecules. So what you actually see is that each of the bonds is about 1.5 times stronger than a single bond which is still weaker than the double bond of oxygen which is about 2 times stronger than a single bond.

HSC would accept drawing one structure and saying that the single bond is weaker than the double bond, making the molecule more reactive because a single coordinate covalent bond is easier to break than a double bond and hence, making it more readily to react and by extension, more reactive but saying that the coordinate covalent bond is weaker, alone, would be incorrect.

 

[Menomaths]

Source: http://www.easychem.com.au/monitoring-and-management/the-atmosphere/allotropes-of-oxygen

 

[someth1ng]

Source: http://www.easychem.com.au/monitoring-and-management/the-atmosphere/allotropes-of-oxygen

What's written there is fine (for HSC). When I read HeroicPandas' response, he said that the coordinate covalent bond was weaker.

That, by itself, isn't correct enough for me to accept because the reason is that it's a single bond, not because it's a coordinate covalent bond.

In addition, I don't think he labelled the coordinate covalent clearly either.

 

[HSC2014]

There is a difference between stability and reactivity (I believe) which you guys aren't addressing.
O3 is less stable than O2 due to weaker overall covalent bonds (UV energy is absorbed by bonds) and hence more easily decomposed. However this does not directly translate to O3 being more reactive to O2.
O3 is more reactive than O2 due to the molecular structure and configuration (creating dipoles - refer to someth1ng's diagram).

So in conclusion, stability and reactivity between the two molecules are due to different things.

(limited knowledge i know nothing about the module so feel free to correct/contribute)

 

[someth1ng]

There is a difference between stability and reactivity (I believe) which you guys aren't addressing.

In chemistry, chemical stability is inversely proportional to chemical reactivity.

That is, higher stability means lower reactivity but apart from that, they mean the same (or you could say opposite) things. It's like how you can describing water with clarity or opacity - they're opposite ways of measuring the same thing.

O3 is more reactive than O2 due to the molecular structure and configuration (creating dipoles - refer to someth1ng's diagram).

Reactivity is largely dictated by bond strength in a molecule and electron configuration and no so much by polarity etc.

 

[HSC2014]

Hmm... what about ethane vs ethene then? From the O3 vs O2 argument, O3 is more reactive due to it's overall weaker intramolecular bonds - however this doesn't apply to ethane.

 

[someth1ng]

Hmm... what about ethane vs ethene then? From the O3 vs O2 argument, O3 is more reactive due to it's overall weaker intramolecular bonds - however this doesn't apply to ethane.

In the O₃ vs O₂ case, we're breaking bonds to decompose it into two different species.
In the CH₂=CH₂ vs C₂H₆, we are breaking a bond and adding atoms for a reaction resulting in one species.

Two completely different situations.

If you wanted to compare reactivity in the same way O₃ vs O₂ were compared, it would be breaking the double bond in ethene compared to breaking the single bond in ethane.

 

[hayabusaboston]

when comparing the reactivity of oxygen and ozone, do i compare bond energies?

yes resonance structure bro

 

[HeroicPandas]

thanks guys