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Strong vs. weak acids and bases?

Posted: Wed Jan 23, 2019 5:51 pm
by AnnaYan_1l
The last time I took chemistry was a couple of quarters ago, so I am a bit lost with identifying acids and bases, and whether they are strong or weak. I am most worried with this test that I will be unable to identify how a compound might dissociate in water. Does anyone have any tips on how to do this? I can do all the calculations for the problems, but I just need help with starting them!

Thanks in advance!

Re: Strong vs. weak acids and bases?

Posted: Wed Jan 23, 2019 6:01 pm
by Nada AbouHaiba 1I
Here's a list of the strong acids and bases! You can assume everything else is weak. Hope this helps!

Re: Strong vs. weak acids and bases?

Posted: Wed Jan 23, 2019 6:02 pm
by Seohyun Park 1L
For me, I memorized the list of strong acids (7 or so please double check) and strong bases ( group 1 and group 2 hydroxides and oxides). The rest are usually weak acids and bases.

Re: Strong vs. weak acids and bases?

Posted: Wed Jan 23, 2019 6:09 pm
by AnnaYan_1l
Thanks! This helps a lot. Follow up question...how do you determine how exactly the weak compounds will dissociate? ex. How would you know that NH2NH2 becomes NH2NH3+?

Thanks again!!!

Re: Strong vs. weak acids and bases?

Posted: Wed Jan 23, 2019 6:19 pm
by Steven Garcia 1H
If the compound has an H+ at its beginning or ends with a -COOH, then you can assume it is an acid. For bases, the compounds will usually contain a hydroxide ion, oxide ion, OR exist as some kind of derivative of ammonia (NH3).

Strong acids include HCl, HI, HBr, HClO4-, HNO3, and H2SO4. You can essentially regard all the other acids as being weak.

Strong bases include metal hydroxides (OH-) and oxides (O2-). All others can be categorized as weak bases.

Re: Strong vs. weak acids and bases?

Posted: Wed Jan 23, 2019 6:25 pm
by Steven Garcia 1H
AnnaYan_1l wrote:Thanks! This helps a lot. Follow up question...how do you determine how exactly the weak compounds will dissociate? ex. How would you know that NH2NH2 becomes NH2NH3+?

Thanks again!!!


Hi! All derivatives of ammonia are weak bases so NH2NH2 is a weak base. Since it's a base, albeit weak, we would expect for a small fraction of the molecules to get protonated to NH2NH3 in an aqueous solution.

Hope this helps!