Jump to content
Sign in to follow this  
grifter

conjugate pairs, Brønsted-Lowry theory

Recommended Posts

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

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.