Wikipedia
Search Wikipedia:

October 2017
MonTueWedThuFriSatSun
      1
2345678
9101112131415
16171819202122
23242526272829
3031     

Calendar Calendar

Free Hit Counter

A buffer question

View previous topic View next topic Go down

A buffer question

Post  Tara on Mon Sep 05, 2011 5:53 am

For example we've got a buffer solution below:
HA <-------> H^+ + A^-
NaA -------> Na^+ + A^-
By adding NaOH (Na^+ and OH^-) to the solution , OH^- would react with H^+ and H^+ decreases. so the equilibrium turns right to increase [H^+] again . so [H^+] doesn't change much.That's our buffer solution.
The question is what is the role of our salt HERE ?

Please explain the role of NaA in MY example. I know the roll of salt when you add an acid. But i don't know NaA's role when adding a base (OH^-)

I used to know the answer but i can't remember it... ... something about Ka ...


Thanks.

Tara

Posts : 1
Join date : 2011-09-05

View user profile

Back to top Go down

Re: A buffer question

Post  charco on Tue Sep 13, 2011 5:02 pm

Tara wrote:For example we've got a buffer solution below:
HA <-------> H^+ + A^-
NaA -------> Na^+ + A^-
By adding NaOH (Na^+ and OH^-) to the solution , OH^- would react with H^+ and H^+ decreases. so the equilibrium turns right to increase [H^+] again . so [H^+] doesn't change much.That's our buffer solution.
The question is what is the role of our salt HERE ?

Please explain the role of NaA in MY example. I know the roll of salt when you add an acid. But i don't know NaA's role when adding a base (OH^-)

I used to know the answer but i can't remember it... ... something about Ka ...


Thanks.

The salt provides a large reservoir of negative A- ions that can 'mop up' any H+ ions that are added. They do not specifically have any role when base is added. (that's what the HA is for)

charco

Posts : 6
Join date : 2011-08-04

View user profile http://www.alevelchem.com

Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum