Weak acid and its salt

Moderators: Chem_Mod, Chem_Admin

rkang00
Posts: 69
Joined: Fri Sep 28, 2018 12:25 am

Weak acid and its salt

Postby rkang00 » Mon Jan 21, 2019 1:13 am

In a problem where we have to calculate the pH of a solution of a weak acid + its salt, do we have to take the cations into account? for example the problem in class professor Lavelle told us - the thing with nitrous acid + potassium nitrite. Do we have to take the potassium ions into account? Or do those not matter?

jessicahe4Elavelle
Posts: 61
Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

Re: Weak acid and its salt

Postby jessicahe4Elavelle » Mon Jan 21, 2019 1:27 am

No, first and second group cations do not affect pH so we shouldn't take them into account. Also the anions Cl, Br and I do not affect pH.

Aarti K Jain 1L
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: Weak acid and its salt

Postby Aarti K Jain 1L » Mon Jan 21, 2019 10:09 am

In general, when creating ICE tables, you are only looking at the molecules that affect pH. Therefore, if a cation/anion does not appear in the acid/base reaction, then one does not have to take the cation/anion into account.

George Ghaly 2L
Posts: 66
Joined: Fri Sep 28, 2018 12:29 am
Been upvoted: 1 time

Re: Weak acid and its salt

Postby George Ghaly 2L » Mon Jan 21, 2019 2:51 pm

As mentioned in 14A, Group 1 mentally and group 17 halogens do not affect the pH of a solution at all. On the other hand group two metals slightly change the pH but not by a drastic amount.


Return to “Equilibrium Constants & Calculating Concentrations”

Who is online

Users browsing this forum: No registered users and 3 guests