Question

why con of H30+ = con of OH- for pure water and neutral solution?

Answer 1

H20

Answer 2

the ions are both charged ± one electron
they cancel each other out, producing water,
some ions will remain in solution

The pH scale is concentration of positive ions , (pOH negative ions),
1x10^7 is the concentration of each of these ion species in water

Answer 3

In addition to what unkle said, a neutral solution consist of equal parts acid and equal parts base. Hence, that is why the conc. of acid (H3O+) and base (OH-) are equal in a neutral solution.

Answer 4

oooohhh! thx!