Kw

Moderators: Chem_Mod, Chem_Admin

Aishwarya Kosgi 1F
Posts: 92
Joined: Wed Sep 30, 2020 10:00 pm

Kw

Postby Aishwarya Kosgi 1F » Tue Jan 12, 2021 12:36 pm

Hi! I had a question about water and it's Kw value of 1x10^-14. Is water considered a strong acid/base? Since it is amphiprotic it can be an acid or a base, but since it has a Kw value, does that make it a weak acid/base? I remember Dr. Lavelle mentioning that only weak acids or bases have Ka values and I was wondering if this applies to water as well. Thanks!

Akshata Kapadne 2K
Posts: 111
Joined: Wed Sep 30, 2020 9:40 pm
Been upvoted: 1 time

Re: Kw

Postby Akshata Kapadne 2K » Tue Jan 12, 2021 1:09 pm

I believe water is both a weak acid and a weak base because it is amphiprotic and it does not ionize completely. So yes, I think you're right that its Kw value indicates that it is weak.

SahajDole_1C
Posts: 96
Joined: Wed Sep 30, 2020 9:33 pm

Re: Kw

Postby SahajDole_1C » Tue Jan 12, 2021 1:43 pm

It is considered as a weak acid and base.

shevanti_kumar_1E
Posts: 90
Joined: Wed Sep 30, 2020 9:40 pm
Been upvoted: 1 time

Re: Kw

Postby shevanti_kumar_1E » Tue Jan 12, 2021 3:22 pm

Yes you are correct water can act as an acid and base because its amphiprotic. Pure water is both a weak acid and base. By itself water only forms a small number of H3O+ and OH- ions so it is considered a weak acid and base.

Juwon Lim 2A
Posts: 91
Joined: Wed Sep 30, 2020 9:49 pm

Re: Kw

Postby Juwon Lim 2A » Tue Jan 12, 2021 5:40 pm

To add on, pure water is neither acidic nor basic. The acid (H3O+) and base (OH-) exist mostly in similar concentrations, so we say water is neutral. However, water can both act as an acid and a base when molecules are in water because of its amphiprotic properties.

Emerald Wong 1B
Posts: 99
Joined: Wed Sep 30, 2020 9:51 pm
Been upvoted: 1 time

Re: Kw

Postby Emerald Wong 1B » Tue Jan 12, 2021 11:15 pm

Water can act as both an acid or a base, but it is weak because it does not ionize completely, so you are correct in your assumptions!

Inderpal Singh 2L
Posts: 150
Joined: Wed Sep 30, 2020 10:02 pm
Been upvoted: 2 times

Re: Kw

Postby Inderpal Singh 2L » Wed Jan 13, 2021 2:33 pm

Since water does not ionize completely, it is considered both a weak acid and base.

If you would like a more in-depth description:

http://chemed.chem.purdue.edu/genchem/t ... nd%20bases.

Adam Bustamante 1I
Posts: 98
Joined: Wed Sep 30, 2020 9:51 pm

Re: Kw

Postby Adam Bustamante 1I » Fri Jan 15, 2021 9:37 am

water can be either an acid or a base and is considered weak because it does not completely ionize.

Rob Tsai 2F
Posts: 94
Joined: Wed Sep 30, 2020 10:09 pm

Re: Kw

Postby Rob Tsai 2F » Sat Jan 16, 2021 4:07 am

Water can act as a weak acid or a weak base, but in terms of pH, it is neutral. The little amounts of H30+ and OH- it does contain is exclusively in equal amounts, so they cancel out. In terms of Ka values, a large Ka value indicates a strong acid, not just any Ka value. Hope this helps!


Return to “Non-Equilibrium Conditions & The Reaction Quotient”

Who is online

Users browsing this forum: No registered users and 2 guests