Inverse Relationship Between H3O+ and OH- [ENDORSED]

[janavi_patel_2K]

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.

[Kareem]

If you can calculate the concentration of OH- you can calculate the concentration of H3O+. Their concentrations multiply out to 1x10^-14.

[Amy_Bugwadia_3I]

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+.