6A.3: Differentiating between acids and bases

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JamieVu_2C
Posts: 108
Joined: Thu Jul 25, 2019 12:16 am

6A.3: Differentiating between acids and bases

Postby JamieVu_2C » Thu Nov 28, 2019 1:44 am

How do you know if a molecule accepts H+ from H2O or donates H+ to H2O without looking at a table? For example, the question asks to Write the chemical equations for the proton transfer equilibria of the following acids in aqueous solution and identify the
conjugate acid–base pairs in each case: (d) HCOOH.

How do you know that HCOOH releases a proton, giving the equation: HCOOH + H2O ->/<- H3O+ + HCO2-?
Why can't it HCOOH accept a proton to give the equation: HCOOH + H2O ->/<- OH- + HCOOH2? How would you be able to differentiate?

MingdaH 3B
Posts: 133
Joined: Thu Jul 11, 2019 12:17 am

Re: 6A.3: Differentiating between acids and bases

Postby MingdaH 3B » Fri Nov 29, 2019 2:21 pm

It's relatively simple to look at the lewis structure of a molecule and see whether or not it'll donate / accept protons for some molecules.

ishaa Diwakar 4E
Posts: 56
Joined: Wed Sep 11, 2019 12:17 am

Re: 6A.3: Differentiating between acids and bases

Postby ishaa Diwakar 4E » Fri Nov 29, 2019 4:29 pm

In this case, the question tells you that this molecule is an acid, and this will usually happen if they are asking about an amphoteric molecule. However, you can determine whether it is an acid or base depending on the molecule. With -COOH molecules, they will usually either be neutral charge or negatively charged from donating a H+, which is why you probably won't see it acting as a base and becoming -COOH2.


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