Question

What is the hydroxyl ion concentration of an acid solution for which [H+]=2,5x10-4?

Answer 1

Well....`K_w=[H_3O^+][HO^-]=10^(-14)` under standard conditions...

Explanation:

And thus...`[HO^-]=K_w/([H_3O^+])=10^-14/(2.5xx10^-4)=4.0xx10^-11*mol*L^-1`

Alternatively, we could use the relationship...

`14=pH+pOH`...

Now `[H_3O^+]=2.5xx10^-14`..and `pH=-log_10[H_3O^+]=-log_10(2.5xx10^-4)=3.60`...

And thus `pOH=14-3.60=11.40`; `[HO^-]=10^(-10.4)*mol*L^-1=4.0xx10^-11*mol*L^-1`