Page 1 of 1

### Inverse Relationship Between H3O+ and OH-

Posted: Sun Nov 20, 2016 9:46 pm
On Pg. 150-151 of the course reader, there is a calculation completed in order to calculate pH and pOH. The equation is Ba(OH)2 --> Ba^2+ + 2OH-. One of the first steps was to find the concentration in H3O+. I understand the how the value was obtained, but I do not understand why the concentration of H30+ was calculated if it is not in the chemical equation.

### Re: Inverse Relationship Between H3O+ and OH-

Posted: Sun Nov 20, 2016 11:44 pm
If you can calculate the concentration of OH- you can calculate the concentration of H3O+. Their concentrations multiply out to 1x10^-14.

### Re: Inverse Relationship Between H3O+ and OH-  [ENDORSED]

Posted: Sun Nov 20, 2016 11:54 pm
H3O+ and OH- are in equilibrium with water. 2H20<-->H3O+ + OH-. Therefore their Kc(written as Kw)=[H3O+][OH-]=1x10^-14. Therefore, in any aqueous system, their concentrations will equal 1x10^-14. Therefore, obtaining the concentration of OH- in the equations above will allow you to obtain the concentration of H3O+.