conjugate pairs, Brønsted-Lowry theory

[grifter]

Brønsted-Lowry denotes that Acids are proton doners and bases are Proton acceptors....fine:

So why is it that a weak acid like HCLO4 can be made by its conjugate pairs H+ and CLO4-

but a strong acid like H2SO4 or HNO3 will not

i.e.

a strong acid can be split in the following way

HCL >>> (H+)(Cl-)

but

(H+)(Cl-) will not join to give HCL

[hotcommodity]

Brønsted-Lowry denotes that Acids are proton doners and bases are Proton acceptors....fine:

So why is it that a weak acid like HCLO4 will split in to its conjugate pairs H+ and CLO4-

but a strong acid like H2SO4 or HNO3 will not

i.e.

a strong acid can be made in the following way

(Cl-)+(H+) >>> HCL

but

HCL will not split to give (CL-) and (H+)

 

[math]HCl[/math] will split to give [math]H^+ + Cl^-[/math] if placed into water. The fact that it completely ionizes means its conjugate base [math]Cl^-[/math] is a weaker base than the [math]H_2O[/math]. This is because the [math]H_2O[/math] is able to attract the [math]H^+[/math] ions more than the [math]Cl^-[/math] ions can. In other words, the stronger the acid, the weaker its conjugate base, and the weaker the acid, the stronger it conjugate base. Since the [math] HClO_4 [/math] you spoke of is a stong acid, it will have a weak conjugate base. If it were a weak acid, it would have a strong conjugate base. This means it will not completely ionize, and thus you'll have a reversible reaction on your hands. Conversely, the HCl placed into water will completely ionize, and the recation will not be a reversible one. I hope that helps.

[grifter]

thanks for the answer hotcommodity im sorry the question i posted was screwed up, i have edited it and the correct one is now at the top

[hotcommodity]

thanks for the answer hotcommodity im sorry the question i posted was screwed up, i have edited it and the correct one is now at the top

 

Don't sweat it. Understand that [math]HCl[/math] is a strong acid, and strong acids completely ionize in water. Both [math]HCl[/math] and [math]H_2O[/math] are polar, which is to say they have both strong negative and positive portions associated with each molecule. When the partial positive portion of the [math]H_2O[/math] molecules cling to the partial negative portions of the [math]HCl[/math] compound, and the partial negative portions of the [math]H_2O[/math] molecules cling to the partial positive portions of the [math]HCl[/math] compound, the[math]HCl[/math] compound is pulled apart. We know that since [math]HCl[/math] is a strong acid, it will have a weak conjugate base [math]Cl^-[/math]. That weak conjugate base is considered weak because it can't hang on to the [math]H^+[/math] ion. If you still have questions feel free to come back.

[grifter]

thats great, thanks Hotcommodity, you really helped clear that up! it was really bugging me

[John Cuthber]

Er?

"So why is it that a weak acid like HCLO4 can be made by its conjugate pairs H+ and CLO4- "

??

HClO4 is an exceptionally strong acid.

[hotcommodity]

Er?

"So why is it that a weak acid like HCLO4 can be made by its conjugate pairs H+ and CLO4- "

??

HClO4 is an exceptionally strong acid.

 

The site construction screwed up the LaTex, grrrr >:|

 

HClO4 is not a weak acid. When placed in water, it completely ionizes, and never returns to its old form, just as all other strong acids do.