Question

`3.00x106^-3` mol of HBr are dissolvedin water to make 16.0 L of solution. What is the concentration of hydroxide ions, [OH-] in this solution?

Answer 1

We use the relationship `pH+pOH=14` in aqueous solution.

Explanation:

Hydrogen bromide is conceived to dissociate entirely in aqueous solution:

`HBr stackrelcolor(blue)(H_2Ocolor(white)(X))(→) H_3O^(+) + Br^(-)`

And thus `[H_3O^+]="Moles of acid (mol)"/"Volume of solution (L)"`

`=(3.00xx10^-3*mol)/(16.0*L)=1.88xx10^-4*mol*L^-1.`

And so `pH=-log_10(1.88xx10^-4)=3.73`.

`pOH=14-3.73=10.27`

And thus `[HO^-]=10^(-10.27)*mol*L^-1=5.33xx10^-11*mol*L^-1`.