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Topic: Weak bases  (Read 6654 times)

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Offline sarah9625

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Weak bases
« on: October 19, 2007, 09:20:55 PM »
What are some examples of weak bases?
 I have google this question and found only one, NH3, there has to be more than that. Do you know of any others?

Offline is3zzz

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Re: Weak bases
« Reply #1 on: October 19, 2007, 09:34:19 PM »
Methylamine is another one i can think of....

Offline Padfoot

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Re: Weak bases
« Reply #2 on: October 19, 2007, 09:56:56 PM »
The conjugates of common strong bases, another common one I know is alanine.

Offline sarah9625

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Re: Weak bases
« Reply #3 on: October 19, 2007, 10:02:08 PM »
I am guessing that there is way more strong bases than weak ones, right?

Offline Padfoot

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Re: Weak bases
« Reply #4 on: October 19, 2007, 10:12:46 PM »
I meant conjugates of common strong ACIDS by the way.

As for:
I am guessing that there is way more strong bases than weak ones, right?
??? I can think of more strong bases than I can weak but this is probably just because I've used strong bases more  :-\

Offline LQ43

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Re: Weak bases
« Reply #5 on: October 19, 2007, 11:26:12 PM »
methylamine is a good start but if you look at the general formula RCH2N, then you can get a ton of weak bases by substituting alkyl groups for R,


there are actually many more weak acids and bases than strong ones. does your textbook not give a list of strong acids, there aren't that many

I'm surprised you can only get NH3 from googling "weak bases"
"http://www.science.uwaterloo.ca/~cchieh/cact/c123/wkacids.html

Offline ashrafabdeljaber

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Re: Weak bases
« Reply #6 on: October 19, 2007, 11:30:08 PM »
Magnesium hydroxide Mg(OH)2 is a weak base

Offline sarah9625

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Re: Weak bases
« Reply #7 on: October 20, 2007, 12:33:51 AM »
Thanks, LQ43 thats exactly what I was trying to find. Here's a snack:)

Offline LQ43

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Re: Weak bases
« Reply #8 on: October 20, 2007, 10:57:28 AM »
Magnesium hydroxide Mg(OH)2 is a weak base

well, strictly speaking, Mg(OH)2 is a slightly soluble ionic compound that also happens to be a base. Whatever amount that is soluble does dissociate 100% so it is in fact a strong base.

Thanks, LQ43 thats exactly what I was trying to find. Here's a snack:)

well, thanks but I should really have prompted you to look again,  ;)

Offline Borek

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Re: Weak bases
« Reply #9 on: October 20, 2007, 11:32:10 AM »
Magnesium hydroxide Mg(OH)2 is a weak base

well, strictly speaking, Mg(OH)2 is a slightly soluble ionic compound that also happens to be a base. Whatever amount that is soluble does dissociate 100% so it is in fact a strong base.

That's not quite true. pK for

Mg2+ + OH- = MgOH+

is somewhere between 2 and 3. That makes Mg(OH)2 in a way comparable with sulphuric acid - strong for the first dissociation step, realitively weak for the second.
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Offline LQ43

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Re: Weak bases
« Reply #10 on: October 20, 2007, 11:35:08 AM »
thanks Borek, that went deeper then I was thinking....

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