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Strong and Weak Acids

Posted: Sun Dec 01, 2019 11:42 am
I understand that strong acids are fully ionized and weak acids are only partially ionized in solution. I get that, but i don't understand how to identify a strong or weak acid. Is there like a list of strong or weak acids that I can just memorize for the final? Or is there a rule of thumb that I'm just not aware of?

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 11:52 am
I think a lot of the time the question will identify if it is strong or weak for you (at least all of the textbook problems do this). But in general stronger acids have a lower pH than weak acids because the bonds in a strong acids are weak which means they can more easily lose H+

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 11:54 am
I would definitely familiarize yourself with a list of both the common weak and strong acids before the final. However, a good rule to test is that strong acids can completely dissociate in a solution, while weak acids can only partly dissociate. For example, HCl, a strong acid, can fully dissociate into H+ and Cl-, while Ch3COOH, a weak acid, only dissociates into Ch3COO- and H+.

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 11:55 am
There is a list of strong acids in the book that I would recommend having memorized!
HBr, HCl, HI, HNO3, HClO4, HClO3, H2SO4

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 12:03 pm
The well-known strong acids are commonly put into a list of seven different molecules:
$HClO_{4}, HClO_{3}, HCl, HBr, HI, HNO_{3},$ and $H_{2}SO_{4}$
These are known as the "7 Strong Acids"

The well-known strong bases are categorized by the name "8 Strong Bases"
They are the Group 1A metal hydroxides (LiOH, NaOH, KOH, RbOH, Cs,OH) and Heavy group 2A metal hydroxides ($Ca(OH)_{2}, Sr(OH)_{2}, Ba(OH)_{2}$)

It's good to know why these are considered strong acids/bases, but it's easiest to memorize the names.

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 3:06 pm
Typical strong acid:
HCl HNO3 H2SO4 HBr HI HClO4 HClO3

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 11:41 pm
Does anyone have a definite answer about if we need to know a list of strong acids and bases?
I remember we are only going to have to determine the pH of strong acids, but will we be asked to identify/ differentiate strong acids from weak acids

Re: Strong and Weak Acids

Posted: Sun Dec 01, 2019 11:59 pm
It is probably best to just memorize the list of strong bases and acids.