HF

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Shreya Patel- 2D
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Joined: Wed Sep 30, 2020 10:01 pm

HF

Postby Shreya Patel- 2D » Sun Dec 06, 2020 7:24 pm

Why is HF a "weak acid"? Shouldn't it be classified as a strong acid?

Ralph Zhang 2L
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Joined: Wed Sep 30, 2020 9:55 pm

Re: HF

Postby Ralph Zhang 2L » Sun Dec 06, 2020 7:37 pm

HF is not a "strong acid" because F is the most electronegative element and holds onto H too well, so this molecule does not dissociate in water very well. It is still pretty corrosive though, despite what the term "weak acid" may suggest.

Eva Becker
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Re: HF

Postby Eva Becker » Sun Dec 06, 2020 7:48 pm

As mentioned, the high electronegativity of flourine creates an incredibly strong bond between the two atoms. Because of this, the acid cannot dissociate easily in water, hence its status as a weak acid. Note that weak acids are not necessarily closer to 7 on the pH scale, they simply cannot dissociate easily in water.

Ansh Patel 2I
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Joined: Wed Sep 30, 2020 9:42 pm

Re: HF

Postby Ansh Patel 2I » Sun Dec 06, 2020 8:03 pm

Hi! Fluorine's high electronegativity makes it extremely hard for the acid to dissociate in water (strongly bonded to H), which is why HF is not a strong acid.

AHUNT_1A
Posts: 110
Joined: Wed Sep 30, 2020 9:41 pm

Re: HF

Postby AHUNT_1A » Sun Dec 06, 2020 8:05 pm

The molecule does not dissociate in water very well, since Fluorine is the most electronegative element creating a tight bond between Fluorine and Hydrogen.

As mentioned before.

ALee_1J
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Joined: Wed Sep 30, 2020 9:32 pm

Re: HF

Postby ALee_1J » Sun Dec 06, 2020 8:11 pm

HF is weak(er) when compared to HI etc. bc of fluorine's high electronegativity and thus strong bond to hydrogen. The stronger the bond, the harder it is to break or dissociate when added to water. How strong an acid or base here is actually inversely related to the bond strength and consequently the electronegativity. Also, the smaller the bond, the stronger the bond and thus the weaker the acid/base. Thus an acid/base is strong when it has low electronegativity or long bonds.

DavidTabib 3H
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Re: HF

Postby DavidTabib 3H » Sun Dec 06, 2020 10:54 pm

Since F has a high electronegativity, the F pulls the electron tight and makes it a weak acid.

Maddie Turk Disc 2J
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Re: HF

Postby Maddie Turk Disc 2J » Tue Dec 08, 2020 10:40 am

Why are acids with short bonds weak acids while acids with long bonds strong acids, and not the other way around?

Eunice_Castro_1G
Posts: 91
Joined: Wed Sep 30, 2020 9:46 pm

Re: HF

Postby Eunice_Castro_1G » Tue Dec 08, 2020 11:04 am

Maddie Turk Disc 2C wrote:Why are acids with short bonds weak acids while acids with long bonds strong acids, and not the other way around?

This is because a strong acid is supposed to give off a proton quite easily, if the there is a strong bond (short bonds) then the electrons and all the rest will be held tightly. Strong acid meaning good at becoming an acid, not meaning the strength it has on pulling. Hope this helps!

reyvalui_3g
Posts: 85
Joined: Wed Sep 30, 2020 9:52 pm

Re: HF

Postby reyvalui_3g » Tue Dec 08, 2020 11:52 pm

This is because F is the most electronegative atom and will not readily give up its hydrogen.

Kiyoka Kim 3C
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Joined: Wed Sep 30, 2020 9:59 pm

Re: HF

Postby Kiyoka Kim 3C » Wed Dec 09, 2020 6:05 am

You would classify a compound being a strong acid if it gives up its proton readily. F is very electronegative so it holds onto its H atom strongly and the bond cannot break easily which means that it cannot donate its proton easily. Therefore HF is a weak acid.

Navdha Sharma 3J
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Joined: Wed Sep 30, 2020 9:46 pm

Re: HF

Postby Navdha Sharma 3J » Wed Dec 09, 2020 7:55 am

HF is a weak acid as F is highly electronegative and does not readily give up proton.

Libby Dillon - 1A
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Re: HF

Postby Libby Dillon - 1A » Wed Dec 09, 2020 12:03 pm

HF was discussed in lecture as a weak acid because it does not easily dissociate, like a strong acid (HCl) would. This is because F is very electronegative and has a shorter, stronger bond.

Jason Knight - 1F
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Joined: Wed Sep 30, 2020 9:55 pm

Re: HF

Postby Jason Knight - 1F » Wed Dec 09, 2020 12:31 pm

HF is considered a weak acid due to the short bond between H-F leaving it more difficult to break, hence being named a weak acid.

Nadya Higgins 3F
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Re: HF

Postby Nadya Higgins 3F » Wed Dec 09, 2020 12:39 pm

The shorter the bond, the stronger the bond. And the stronger the bond, the weaker the acid. HF has quite the short and strong bond due to their difference in electronegativity, so it's classified as a weak acid.

Crystal Pan 2G
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Re: HF

Postby Crystal Pan 2G » Wed Dec 09, 2020 1:47 pm

The bond between HF is very strong because F is very electronegative. A strong acid dissociates/ionizes almost completely. It would be hard for the aqueous solution to dissociate HF, therefore it is not a strong acid.


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