Acids and Bases  [ENDORSED]

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Iris Shim 1E
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Joined: Fri Sep 29, 2017 7:04 am

Acids and Bases

Postby Iris Shim 1E » Sun Oct 29, 2017 7:25 pm

Why do strong conjugate bases mean a weak acid?

Nora Sharp 1C
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Joined: Sat Jul 22, 2017 3:00 am

Re: Acids and Bases  [ENDORSED]

Postby Nora Sharp 1C » Mon Oct 30, 2017 12:14 am

Weak acids create "strong" conjugate bases because their dissociation reaction (the reaction of it releasing an H+ ion) is not favored. If you take HNO2 (nitrous acid) as an example, the reaction for HNO2 to produce a conjugate base would be as follows:

HNO2 = H+ + NO2-

In this case, NO2- is the conjugate base.
Because HNO2 is a weak acid, not a lot of it dissociates. In other words, it is favored that HNO2 remains together as a molecule and does not release H+ ions. Some HNO2 molecules do dissociate but most do not. This means that NO2- is a strong base because the back reaction (the reaction that causes it to become HNO2 again) is favored. Keep in mind this definition of "strong base" doesn't apply in the "bases that dissociate completely to release OH-" sense of the term, it just means that relative to HNO2 as a weak acid, NO2- is a strong base.

Essly Mendoza 1J
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Re: Acids and Bases

Postby Essly Mendoza 1J » Tue Dec 05, 2017 12:38 am

Hello, how can we tell if the acid is a strong acid or a weak acid?

Anna Goldberg 2I
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Re: Acids and Bases

Postby Anna Goldberg 2I » Tue Dec 05, 2017 12:48 am

A strong acid is an acid in which almost all of the molecules are deprotonated in solution. A weak acid is an acid in which only a small fraction of the molecules become deprotonated in solution.

Lauryn Jordan 1F
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Re: Acids and Bases

Postby Lauryn Jordan 1F » Tue Dec 05, 2017 12:50 am

there is a list of strong acids, if it is not one of those, it is considered weak. the list of strong acids include HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4

Anna Goldberg 2I
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Re: Acids and Bases

Postby Anna Goldberg 2I » Tue Dec 05, 2017 12:53 am

Will we receive a list similar to this on the final? (I am assuming not).

Lauryn Jordan 1F
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Re: Acids and Bases

Postby Lauryn Jordan 1F » Tue Dec 05, 2017 1:04 am

I honestly don't know, but I doubt it. I was told to memorize them by my plf. There's also a list of strong bases. LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2

Essly Mendoza 1J
Posts: 25
Joined: Fri Sep 29, 2017 7:04 am

Re: Acids and Bases

Postby Essly Mendoza 1J » Tue Dec 05, 2017 2:34 am

I think we may be expected to know the most common strong acids and weak acids.

Evelyn L 1H
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Re: Acids and Bases

Postby Evelyn L 1H » Tue Dec 05, 2017 11:46 am

Everything that isn't a strong base or strong acid (which were listed above) is considered weak.


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