What is [OH-] for a 4.72 X 10^-9M HCL solution?

Question

Would I just take 1.0X10-14 divided by 4.72X10-9?

Answer 1

HCl is a strong acid, so yes. The concentration of HCl is equivalent to the concentration of H3O^+ in solution.

10^-14=[H3O^+][OH^-]

[H3O^+]= 4.72 X 10^-9 M

[OH^-]=10^-14/4.72 X 10^-9 M