Why is HF not classified as a strong acid?

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Arnav Saud 2C
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Why is HF not classified as a strong acid?

Postby Arnav Saud 2C » Wed Dec 02, 2020 6:34 pm

The general trend of the hydrohalic acids (HCl, HBr, HI) is that HCl is stronger than HBr and HI is stronger than HBr. These 3 acids are all classified as strong as well. Why is HF not classified as a strong acid? What property of HF causes it to not completely dissociate in solution(be classified as a weak acid)?

Olivia Yang 3J
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Re: Why is HF not classified as a strong acid?

Postby Olivia Yang 3J » Wed Dec 02, 2020 8:51 pm

Since F is so electronegative, it holds on tightly to the H (stronger and shorter bond) making it hard to dissociate.

rachelhchem1I
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Re: Why is HF not classified as a strong acid?

Postby rachelhchem1I » Wed Dec 02, 2020 9:35 pm

HF initially almost completely disassociates, but after, it participates in other reactions with itself and with water, essentially unassociating the acid and then behaving like a weak acid

Kayla Law 2D
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Re: Why is HF not classified as a strong acid?

Postby Kayla Law 2D » Sat Dec 05, 2020 3:40 pm

I believe that HF is considered a weak acid since it doesn't lose the H+ easily. This is due to F's electronegativity and the fact that the bond between H and F is short since F has a small atomic radius. Because the bond is short, the bond is stronger, and it is harder for the HF to lose its H+, making it a weak acid.

Andre Fabian 1F
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Re: Why is HF not classified as a strong acid?

Postby Andre Fabian 1F » Sat Dec 05, 2020 3:59 pm

Strong acids are characterized by their ability to dissociate completely into H+ ions. HF has an extremely short bond because of its small atomic radius (thus the nucleus of Fluorine has a greater pulling power), as well as it's high electronegativity. Because of HF's properties, HF is unable to completely dissociate into its constituent H+ and F- ions, and is thus a weak acid.


Hope this helps!
Andre

VSU_3F
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Re: Why is HF not classified as a strong acid?

Postby VSU_3F » Sat Dec 05, 2020 4:01 pm

As others have mentioned, it is extremely hard for HF to dissociated into its constitutive ions as it is the smallest atom out of all the others. Since how easily a bond dissociates is a measure of how strong an acid is, with easier dissociations equating to stronger acids, HF is not considered a strong acid.

Chinyere Okeke 2J
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Re: Why is HF not classified as a strong acid?

Postby Chinyere Okeke 2J » Sat Dec 05, 2020 4:22 pm

Strong acids are classified by the degree of dissociation in solution. HF not only has a short bond (which makes it harder to dissociate) it also has an F- (which has high electronegativity). Therefore, HF is unable to completely dissociate into H+ and F- making it a weak acid.

Madison Muggeo 3H
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Re: Why is HF not classified as a strong acid?

Postby Madison Muggeo 3H » Sat Dec 05, 2020 5:44 pm

Hi! The bond length between H and F is shorter than the other bonds mentioned, and additionally, F is very electronegative so it is difficult for it to completely dissociate. Strong acids are easily dissociable, due to their longer and weaker bonds and closer electronegativity differences (in this example).

Astha Sahoo 3I
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Re: Why is HF not classified as a strong acid?

Postby Astha Sahoo 3I » Sat Dec 05, 2020 6:35 pm

In the textbook, it mentions that for binary acids especially, as you go down a group, the acid becomes stronger, since the bond enthalpy is lower. Thus, since F is at the top of the fluorine group, it's forms the weakest acid with H. All elements above Br form weak binary acids with hydrogen.

AJForte-2C
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Re: Why is HF not classified as a strong acid?

Postby AJForte-2C » Sun Dec 06, 2020 6:16 pm

Fluorine is extremely electronegative, so it's much harder for it to dissociate. This means it's considered a weak acid, because acid strength is determined by their ability to dissociate in water.

Ximeng Guo 2K
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Re: Why is HF not classified as a strong acid?

Postby Ximeng Guo 2K » Sun Dec 06, 2020 7:22 pm

The H-F bond is short and strong, which makes HF harder to give out protons. Thus weak acid.

IshanModiDis2L
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Re: Why is HF not classified as a strong acid?

Postby IshanModiDis2L » Sun Dec 06, 2020 7:25 pm

Strong acids are characterized by their ability to dissociate completely into H+ ions. F is so electronegative with a short bond length to the Hydrogen so it will not want to fully dissociate that easily.

Justin Zhang_1A
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Re: Why is HF not classified as a strong acid?

Postby Justin Zhang_1A » Sun Dec 06, 2020 7:34 pm

Since F is very electronegative, it is much harder for HF to dissociate into H+ ions, making it a weak acid.

Keshav Patel 14B 2B
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Re: Why is HF not classified as a strong acid?

Postby Keshav Patel 14B 2B » Sun Dec 06, 2020 8:09 pm

HF cannot be classified as a strong acid because fluorine has the highest electronegativity on the periodic table of element so it holds onto that hydrogen very tightly making it not a strong acid, but do not forget it is still an acid.

Adrienne Chan 1G
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Re: Why is HF not classified as a strong acid?

Postby Adrienne Chan 1G » Sun Dec 06, 2020 8:12 pm

My guess is that since fluorine is so electronegative, it doesn't let go of the electron as easily as other halogens might. This would make it harder for HF to dissociate in water, and so weaken the acid, thus making it not a strong acid.

Aayushi Jani 3A
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Re: Why is HF not classified as a strong acid?

Postby Aayushi Jani 3A » Mon Dec 07, 2020 9:59 am

HF is not a strong acid as F is so electronegative, which means that HF does not easily dissociate into H+ and F- easily in water. This is why, as atomic radius increases, the acids become stronger as they are able to dissociate much easier.

Nhu Pham-Dis3G
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Re: Why is HF not classified as a strong acid?

Postby Nhu Pham-Dis3G » Mon Dec 07, 2020 2:49 pm

HF is not classified as a strong acid because its ability to dissociate to donate proton is low.

CesarLec1
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Re: Why is HF not classified as a strong acid?

Postby CesarLec1 » Mon Dec 07, 2020 7:12 pm

It is not classified as a strong acid due to how the strength of the H-F bond. Since it is stronger than the rest of the halogens, it does not break as easily therefore it does not dissociate nearly as much as the strong acids.

505352202
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Re: Why is HF not classified as a strong acid?

Postby 505352202 » Mon Dec 07, 2020 10:58 pm

I am not sure if this was already mentioned, but the bond length of HF is pretty short, so it makes it harder to break that bond. Shorter bonds = stronger bonds = weaker acids.

Emerald Wong 1B
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Re: Why is HF not classified as a strong acid?

Postby Emerald Wong 1B » Tue Dec 08, 2020 12:31 am

Fluorine is so electronegative that it holds onto its electrons, so it will not let go of that hydrogen easily. Strong acids are those that will give up the hydrogen easily, so HF is not a strong acid.


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