Determining if something is a strong acid

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Isabella Sanzi 2E
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Joined: Thu Jul 13, 2017 3:00 am

Determining if something is a strong acid

Postby Isabella Sanzi 2E » Mon Dec 04, 2017 9:42 pm

Hello everyone!
So today in class we talked about properties that make acids strong. I am a bit confused on what it meant when Dr. Lavelle said that the resulting anion must be stable relative to the neutral form. What does this mean exactly, and how do I tell if an anion is stable?
Also, we went through some examples dealing with three different acids (hypochlorous acid, hypobromous acid, and hypoiodous acid) and talked about electron withdrawing atoms but I am also confused on what that means exactly and how this makes an acid strong.
Thanks everyone!

Chem_Mod
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Re: Determining if something is a strong acid

Postby Chem_Mod » Tue Dec 05, 2017 12:35 am

A strong acid would be a molecule that, when it dissociates, produces H+ and a relatively stable conjugate base. This conjugate base (or resulting anion) must be stable relative to the neutral form in order to make the acid that made it strong. For example, H2SO4 is a strong acid because it has resonance in its conjugate base that stabilizes the conjugate base (forming this stable compound is what drives this reaction forward - hence, why the acid readily deprotonates).

Electron withdrawing atoms refers to the halogens in those compounds. Because they are electronegative, they withdraw electrons away from the oxygen atom they are attached to through a property called induction (inductive effect). Taking electron density away from that oxygen makes the overall compound a better acid, since this would weaken the bond between hydrogen and that oxygen. Thus, hypochlorous acid (HOCl) would be a stronger acid than hypobromous acid (HOBr).

Justin Chu 1G
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Re: Determining if something is a strong acid

Postby Justin Chu 1G » Tue Dec 05, 2017 9:14 am

It might also be a good idea to just remember some of the more common strong acids such as HCl, HBr, HI, HNO3, H2SO4, and HClO4.

Essly Mendoza 1J
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Re: Determining if something is a strong acid

Postby Essly Mendoza 1J » Tue Dec 05, 2017 1:03 pm

If we're looking at Lewis Structures how can we tell that one acid is stronger than the other? What should we be looking for? Thank you.


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