Question

4.00×10−3 mol of HBr are dissolved in water to make 14.0 L of solution. What is the concentration of hydroxide ions, [OH−], in this solution?

Answer 1

Answer: The concentration of hydroxide ions is 3.5 x 10^-11 M.

Step-by-step explanation:

HBr is a strong acid, thus the concentration of HBr wil be the same of H+ ions. Then, we have to calculate the H+ concentration:

`[H^(+)]=(mol H^(+))/(L of solution) = (4.00*10^(-3) mol )/(14.0 L) =0.000286 M [H^(+)]`

Now, we can calculate the pH of the solution:

`pH=-log[H^(+)]=-log [0.000286]=3.54`

With the pH, now we can obtain the pOH value:

`pOH= 14 - pH = 14 - 3.54 = 10.46`

Finally, we can calculate the OH- concentration with the pOH formula:

`pOH=-log[OH^(-)]`

`[OH^(-)]=10^(-pOH) = 10^(-10.46) = 0.000000000035 M [OH^(-)]= 3.5*10^(-11) M [OH^(-)]`

Therefore, the concentration of hydroxide ions is 3.5 x 10^-11 M.