Determining Acidic Character: Oxoacids and Polarization?

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Ayesha Aslam-Mir 3C
Posts: 118
Joined: Wed Sep 30, 2020 9:43 pm

Determining Acidic Character: Oxoacids and Polarization?

Postby Ayesha Aslam-Mir 3C » Thu Dec 10, 2020 12:25 am

So on sapling question 11 for this week, the feedback I got after getting it wrong (LOL yall pray for me on this final) was that "stronger oxoacids contain more polarized O-H bonds. The more electronegative the central atom, the more polarized the O-H bond will be."

I'm confused on how this is true when earlier in the course we learned that thelarger the O-H bond going down group 7, the more acidic (technically) it'd be ebcause it's easier for the electron cloud to dro the proton. Why, then, are more polarized O-H bonds in oxoacids more acidic?

Ayesha Aslam-Mir 3C
Posts: 118
Joined: Wed Sep 30, 2020 9:43 pm

Re: Determining Acidic Character: Oxoacids and Polarization?

Postby Ayesha Aslam-Mir 3C » Thu Dec 10, 2020 12:25 am

(slightly related but in addition why isn't HF a strong acid?)

Nina Tartibi 1F
Posts: 52
Joined: Wed Sep 30, 2020 9:58 pm

Re: Determining Acidic Character: Oxoacids and Polarization?

Postby Nina Tartibi 1F » Thu Dec 10, 2020 1:50 pm

HF is not a strong acid because when dealing with hydrohalic acids, you distinguish the strength by atomic radius. F is one of the smallest atoms on the periodic table, and it's the smallest out of the halogens, so therefore it isn't a strong acid, and acids such as HCl, HBr, and HI are all stronger.

For oxoacids, one of the rules we need to know is that the more oxygens, the stronger the acids. You also take into account that for oxoacids, you look at the polarity, for example HBrO2 vs. HClO2, HClO2 is a stronger acid because Cl is more electronegative than Br, and you look at electronegativity in oxoacids, but for hydrohalic acids you'd look at size.


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