Weak Bases

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Weak Bases

Postby 604805638 » Sun Nov 20, 2016 11:51 pm

Why are weak bases like NH3 not completely ionized? What forces them to not completely dissociate?

Sandra Maesta 1C
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Re: Weak Bases

Postby Sandra Maesta 1C » Mon Nov 21, 2016 11:35 am

So, it has to do with the equilibrium constants. You see, molecules in a solution are constantly dissociating and reprotonating, and the relative stability of the acid and conjugate base, represented by equilibrium constants, determines the rate of the forward and backward reactions, right? So, equilibrium being a reversible process, the system (the molecules dissociation and reprotonation) is actually a flux. That being said, weaker bases have lower equilibrium constants (considering the forward equation one in which the reactant is the base and the results are the ions OH- and the conjugate bases), which makes their forward reaction less common than the backwards one, which is why there is more reactant (base) than product (dissociated base).

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Re: Weak Bases

Postby edward_qiao_3I » Mon Nov 28, 2016 10:00 am

Additionally, weak bases are weak bases because they are more stable and are less likely to take another H to form the conjugate acid, and therefore will result in less production of OH- when combined in an aqueous solution.

Wayland Leung
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Re: Weak Bases

Postby Wayland Leung » Wed Nov 29, 2017 10:04 pm

How do you determine just by looking at a molecule that it is a weak base?

Charles Ang 1E
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Re: Weak Bases

Postby Charles Ang 1E » Fri Dec 01, 2017 10:35 am

Wayland Leung wrote:How do you determine just by looking at a molecule that it is a weak base?

I'm not quite sure, but I do know that there is chart towards the end of the course reader, right before the sample tests, listing common weak bases.

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