Weak vs. Strong Acids and Bases

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Carolina Gomez 2G
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Joined: Wed Sep 30, 2020 9:32 pm

Weak vs. Strong Acids and Bases

Postby Carolina Gomez 2G » Sun Jan 17, 2021 10:57 pm

How do we identify when solving for pH when the equation deals with strong acids/ bases or weak acids/ bases?

Xinyu Li 1C
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Re: Weak vs. Strong Acids and Bases

Postby Xinyu Li 1C » Sun Jan 17, 2021 11:05 pm

There is a list of strong acids and bases in the textbook. But generally, strong acids will contain halogens (Cl, Br, I) and strong bases will contain elements from group 1 & 2 (Li, Na, K, Rb, Cs, Ca, Sr, Ba).

https://sites.google.com/site/chempendi ... #h.p_ID_32

Tracey Huynh 2F
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Joined: Wed Nov 18, 2020 12:19 am

Re: Weak vs. Strong Acids and Bases

Postby Tracey Huynh 2F » Wed Jan 20, 2021 12:32 am

Xinyu's link is a great resource, where strong acids and bases completely dissociate when reacting with water, in which the [H30+] or [OH-] would be equivalent to the concentrations of the strong acids or bases. [H30+] and [OH-] can then be used to solve for pH. Otherwise, with weak acids and bases, the problem will usually provide us with an initial condition of the acid and the Kb or Ka value, which we can use to determine the concentration of [H3O+] or [OH-]. I believe that for the 6D problems in the textbook, the book requires you to utilize tables 6C.1 and 6C.2 for the Ka, Kb, pKa, and pKb values for certain weak acids and bases.

Kathy_Li_1H
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Joined: Wed Sep 30, 2020 9:31 pm

Re: Weak vs. Strong Acids and Bases

Postby Kathy_Li_1H » Thu Jan 21, 2021 1:12 pm

Hi! For me to remember the strong acids and bases, I find it easiest to just use quizlet/flash cards to memorize them. Since there are a lot less strong acids and bases than their weak counterparts, I would just suggest knowing the strong acids and bases rather than trying to memorize the weak acids and bases.

Strong Acids: HCl, HBr, HI, HClO3, HClO4, HNO3, H2SO4
Strong Bases: Group 1 hydroxides, Ca(OH)2, Sr(OH)2, Ba(OH)2, Group 1 and 2 oxides

Kelly Singh
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Re: Weak vs. Strong Acids and Bases

Postby Kelly Singh » Thu Jan 21, 2021 2:32 pm

Xinyu Li 1C wrote:There is a list of strong acids and bases in the textbook. But generally, strong acids will contain halogens (Cl, Br, I) and strong bases will contain elements from group 1 & 2 (Li, Na, K, Rb, Cs, Ca, Sr, Ba).

https://sites.google.com/site/chempendi ... #h.p_ID_32



Thank you for this.

jessicasilverstein1F
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Joined: Wed Sep 30, 2020 9:57 pm

Re: Weak vs. Strong Acids and Bases

Postby jessicasilverstein1F » Thu Jan 21, 2021 7:11 pm

Unfortunately the only way to know whether something is a strong/weak acid/base is to memorize them!

Felicia Wei 1B
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Joined: Wed Nov 18, 2020 12:28 am

Re: Weak vs. Strong Acids and Bases

Postby Felicia Wei 1B » Thu Jan 21, 2021 10:24 pm

You will know when something is a weak base or acid in an equation when the product consists of the ions that form those acids/bases. for example HCl will form H3O+ and Cl-

Tanner Bartyczak 1K
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Joined: Wed Sep 30, 2020 9:51 pm

Re: Weak vs. Strong Acids and Bases

Postby Tanner Bartyczak 1K » Sat Jan 23, 2021 2:18 am

Yes, sadly it is almost necessary to memorize them, but there are a list of rules that are followed by most strong acids and bases.

Gustavo_Chavez_1K
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Joined: Wed Sep 30, 2020 9:46 pm

Re: Weak vs. Strong Acids and Bases

Postby Gustavo_Chavez_1K » Sun Jan 24, 2021 5:49 pm

I would say that the only and probably easiest way is to just memorize the list of strong acids and bases. With this all the acids and bases that aren't listed as strong would be considered weak.

Arnav Saud 2C
Posts: 117
Joined: Wed Sep 30, 2020 9:51 pm

Re: Weak vs. Strong Acids and Bases

Postby Arnav Saud 2C » Sun Jan 24, 2021 7:26 pm

The best method is to memorize all of the strong acids and strong bases. Everything else is considered as a weak acid or base.


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