Acids and Bases

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Savannah Mance 4G
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Joined: Fri Aug 30, 2019 12:17 am

Acids and Bases

Postby Savannah Mance 4G » Tue Jan 21, 2020 3:25 pm

How do you know whether a molecule is an acid or a base? I was doing the problems in 6D and I didn't know how to set up some of the equilibrium equations because I didn't know if they were acids or bases. Is there a way to tell?

Brian Tangsombatvisit 1C
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Joined: Sat Aug 17, 2019 12:15 am

Re: Acids and Bases

Postby Brian Tangsombatvisit 1C » Tue Jan 21, 2020 3:28 pm

Acids donate their protons and are usually written as HA, where A is the rest of the molecule. Bases accept protons and usually have an OH somewhere within the molecule (an exception to this is the weak base NH3). Really long molecules with an amine group (NH2) are usually bases as the nitrogen atom in this group tends to accept protons from water to produce OH-. Molecules with a carboxyl group (COOH) donate their proton to water and act as an acid.

Vicki Liu 2L
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

Re: Acids and Bases

Postby Vicki Liu 2L » Tue Jan 21, 2020 3:30 pm

I think one clue is a molecule’s charge. Acids are proton donors so they tend to be positive. Bases are proton acceptors so they tend to be negative.

Victoria Zheng--2F
Posts: 103
Joined: Fri Aug 09, 2019 12:17 am

Re: Acids and Bases

Postby Victoria Zheng--2F » Tue Jan 21, 2020 3:33 pm

For the salts in topic 6D, their acidity and basicity depend on whether cations and anions affect the pH of the solution. If the cations are in group I and group II, then they generally do not affect the pH of the solution. If parts of the salt are the conjugate acid of a weak base, then it would make the solution acidic, and if parts of the salt are the conjugate base of a weak acid, then it would make the solution basic. The conjugate acid of strong bases and the conjugate bases of strong acids do not affect pH.

Kaylee Clarke 1G
Posts: 103
Joined: Fri Aug 30, 2019 12:15 am

Re: Acids and Bases

Postby Kaylee Clarke 1G » Tue Jan 21, 2020 5:29 pm

There are a small amount of strong acids and bases that you should have memorized. Otherwise, acids are proton donors and usually produce hydronium. Bases are proton acceptors and produce hydroxide.

Joseph Saba
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Joined: Thu Jul 11, 2019 12:16 am

Re: Acids and Bases

Postby Joseph Saba » Tue Jan 21, 2020 6:45 pm

Will we be given equations on test 1 or will we have to infer whether the molecule acts as an acid or a base?

Astrid Lunde 1I
Posts: 103
Joined: Sat Sep 07, 2019 12:16 am

Re: Acids and Bases

Postby Astrid Lunde 1I » Tue Jan 21, 2020 8:13 pm

Acids donate protons and bases accept protons.

BNgo_2L
Posts: 95
Joined: Wed Sep 11, 2019 12:17 am

Re: Acids and Bases

Postby BNgo_2L » Tue Jan 21, 2020 8:45 pm

We learned in 14A how to determine if a molecule is an acid or base. You can determine by its characteristics. Lewis acids accept electron pairs, so they tend to have a negative charge (Lewis acid), produce H3O+ (Arrhenius acid), and donate H+ (Bronsted acid). On the other hand, bases donate electron pairs (tend to have a positive charge), produce OH-, and accept H+.


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