pH change

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Amy Perez 2K
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

pH change

Postby Amy Perez 2K » Thu Dec 03, 2015 7:24 am

How do you know which molecules do not affect the pH of a solution?

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

Re: pH change

Postby kshalbi » Thu Dec 03, 2015 2:40 pm

Most of them are in the course reader, but they're the halogen anions, alkali metal cations, and alkali earth metal cations. It's on page 147 of the course reader.

Heerali Patel 3A
Posts: 26
Joined: Fri Sep 25, 2015 3:00 am

Re: pH change

Postby Heerali Patel 3A » Thu Dec 03, 2015 3:34 pm

Generally, salts that contain cations from groups 1 and 2 (e.g. NaCl) do not affect pH because these cations are weak lewis acids. Additionally, acidic salts (e.g. NH4Cl) will lower the pH of a solution because of the acid (NH4+ of NH4Cl) reacting with water to form H3O+, but the anion (the halogen Cl- in NH4Cl) will not affect the pH. This same reasoning goes for basic salts (e.g. the base CH3CO2- in NaCH3CO2 will mix with water to form OH- to raise the pH but the cation Na+ of this molecule will not affect pH).


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