How to determine which is an acid and which is a base?

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Alyssa_Hsu_2K
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Joined: Wed Sep 21, 2016 3:00 pm

How to determine which is an acid and which is a base?

Postby Alyssa_Hsu_2K » Fri Nov 25, 2016 4:06 pm

Say we were only given NH3(aq), and asked what is its conjugate acids and conjugate base.
I know acids are the proton donors and bases the proton acceptors. However, in this case, how would we know whether NH3 or H2O is the proton donor or acceptor?
Seeing that Oxygen is more electronegative than Nitrogen, why isn't the H from NH3 going to H2O?

Janette 3B
Posts: 10
Joined: Fri Jul 15, 2016 3:00 am

Re: How to determine which is an acid and which is a base?

Postby Janette 3B » Fri Nov 25, 2016 9:18 pm

In this case you NH3 is a weak base due to the fact that NH3 is not completely ionized in water

604805638
Posts: 19
Joined: Wed Sep 21, 2016 2:59 pm

Re: How to determine which is an acid and which is a base?

Postby 604805638 » Sat Nov 26, 2016 3:07 pm

Do we just have to memorize the strong bases in order to know that NH3 is a weak base?

Anna Makridis_L1
Posts: 13
Joined: Fri Jul 01, 2016 3:00 am

Re: How to determine which is an acid and which is a base?

Postby Anna Makridis_L1 » Sun Nov 27, 2016 3:59 pm

Also NH3 has a lone pair. I think this may be the reason it bonds with the other hydrogen

Katherine_Zhuo_3B
Posts: 23
Joined: Wed Sep 21, 2016 2:57 pm

Re: How to determine which is an acid and which is a base?

Postby Katherine_Zhuo_3B » Sun Nov 27, 2016 11:58 pm

Given NH3 (aq), by memorizing the strong/weak acids and bases, we know that NH3 is a weak base. The lone pair on the nitrogen will bond with neighboring hydrogens from the H2O to form conjugate acid NH4+ and conjugate base OH-.

Logan 3C
Posts: 22
Joined: Wed Sep 21, 2016 2:57 pm

Re: How to determine which is an acid and which is a base?

Postby Logan 3C » Mon Nov 28, 2016 12:08 am

It's really really helpful if you memorize the list in the course reader. Other than that if you think about which one of the two reactants will be more likely to give up a Hydrogen, that is acid. It takes a little bit of thinking ahead for me, but once you consider that it is easier.


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