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Strong Acids/Bases

Posted: Wed Dec 06, 2017 7:18 am
by Nha Dang 2I
During review session yesterday, they mentioned that strong acids/bases don't have conjugate bases/acids? Can someone explain this?

Re: Strong Acids/Bases  [ENDORSED]

Posted: Wed Dec 06, 2017 8:50 am
by Chem_Mod
You could think of the strong acid HCl as having Cl- as a conjugate base. However, it is an extremely, extremely, weak conjugate base. We assume 100% dissociation and no reverse reaction for the acid/base reactions of STRONG acids and bases so according to that assumption, the Cl- ion in HCl would not be a base at all. It makes no sense to call it a conjugate base.

In the cases of weak acids and bases, yes, they have conjugates and the reaction is an equilibrium.

Re: Strong Acids/Bases

Posted: Wed Dec 06, 2017 11:21 am
by Cali Rauk1D
do we need to memorize what are strong/weak acids and bases?

Re: Strong Acids/Bases

Posted: Wed Dec 06, 2017 12:27 pm
by Victoria Draper 1G
Cali Rauk1D wrote:do we need to memorize what are strong/weak acids and bases?

I don't think we need to memorize a list of strong/weak acids or bases but we should know the characteristics of what makes an acid or a base weak or strong. Knowing those characteristics will help in identifying a molecule as being an acid or a base as well as the strength of their bond.

Re: Strong Acids/Bases

Posted: Thu Dec 07, 2017 12:56 am
by Jana Sun 1I
Although we might not HAVE to memorize them, I've found that in past chemistry classes it oftentimes makes problems easier to memorize them. In addition to understanding their characteristics (as mentioned in the previous post), it might be easier to just know a few strong acids (HCl, Hbr, HI, etc.) and a few strong bases (all alkali metal hydroxides, heavy group 2A metal hydroxides like Ca(OH)2, Sr(OH)2, and Ba(OH)2).

Re: Strong Acids/Bases

Posted: Thu Dec 07, 2017 4:50 am
by Nha Dang 2I
For strong acids, it's best to memorize the seven (HCl, HBr, HI, HNO₃, H₂SO₄, HClO3, HClO₄), and I believe it's usually assumed all other acids are weak acids.