Identifying a strong acid

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Abbey Kerscher 3O
Posts: 24
Joined: Fri Jul 22, 2016 3:00 am

Identifying a strong acid

Postby Abbey Kerscher 3O » Tue Nov 29, 2016 12:33 pm

What is the cut off for an acid to be a strong acid versus being a weak one? Is a strong acid only 1 or 2 on the pH scale?

Tara_Shooshani_3N
Posts: 29
Joined: Wed Sep 21, 2016 3:00 pm

Re: Identifying a strong acid

Postby Tara_Shooshani_3N » Tue Nov 29, 2016 12:40 pm

I don't think that strong and weak acids and bases are determined based on a set number on the pH scale because temperature and solvent change pH. Instead, a strong acid/base is one that completely ionizes in a reaction. A weak acid/base does not completely ionize. You can tell in a question whether you are dealing with weak acids or bases because you will be given a Ka or Kb value, indicating that the molecule does not completely dissociate.

Jared Gao 3G
Posts: 16
Joined: Wed Sep 21, 2016 2:58 pm

Re: Identifying a strong acid

Postby Jared Gao 3G » Tue Nov 29, 2016 1:47 pm

Are we expected to be able to recognize and remember all of the strong and weak acids/bases given to us in the course reader?

Jata_Kavya_3A
Posts: 22
Joined: Wed Sep 21, 2016 2:57 pm

Re: Identifying a strong acid

Postby Jata_Kavya_3A » Tue Nov 29, 2016 4:53 pm

How can we immediately recognize if its a strong acid or weak acid, without memorizing them?

Chem_Mod
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Re: Identifying a strong acid

Postby Chem_Mod » Tue Nov 29, 2016 6:41 pm

It's not good to go by pH to determine if an acid is strong, since molarities vary.

You will be expected to know what the main strong acids are (HI, HBR, HCl, HClO4, HClO3, H2SO4, HNO3).

You can know if it's a strong acid by looking at the Ka. Generally, if it's greater than 1 it is a strong acid, as seen here:

http://depts.washington.edu/eooptic/lin ... ength.html

Caitlin Dillon 3G
Posts: 26
Joined: Wed Sep 21, 2016 2:56 pm

Re: Identifying a strong acid

Postby Caitlin Dillon 3G » Tue Nov 29, 2016 8:57 pm

I was struggling trying to memorize the 7 strong acids we need to memorize! I looked up easy ways to remember them and I found this, it is so helpful!


Someone posted:
"My chemistry teacher taught us a way to memorize the strong acids. I hope this is helpful:
"[I] [Br]ought [Chlorine] into the forest, 10 year laters, so far, no trees only clovers"
-So far, is like... S O fOUR [SO4]
-No trees, N O tREE [NO3]
-Clovers, Cl-O-fourss [ClO4]
then just add H in front of each, the I, Br, Cl, SO4, NO3 and ClO4"

Seriously just write this over a couple of times on a piece of paper and it sticks.

Julia Hwang 3G
Posts: 22
Joined: Wed Sep 21, 2016 3:00 pm

Re: Identifying a strong acid

Postby Julia Hwang 3G » Wed Nov 30, 2016 12:22 pm

omg such a helpful pneumonic! will definitely be using this thanks :)


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