Answer: The hydroxide ion concentration and pOH of the solution is
and 2.88 respectively
Step-by-step explanation:
We are given:
Concentration of barium hydroxide = 0.00066 M
The chemical equation for the dissociation of barium hydroxide follows:

1 mole of barium hydroxide produces 1 mole of barium ions and 2 moles of hydroxide ions
pOH is defined as the negative logarithm of hydroxide ion concentration present in the solution
To calculate pOH of the solution, we use the equation:
![pOH=-\log[OH^-]](https://img.qammunity.org/2021/formulas/chemistry/high-school/aptpm2b2equoweomw80psbpn50765hcb2n.png)
We are given:
![[OH^-]=(2* 0.00066)=1.32* 10^(-3)M](https://img.qammunity.org/2021/formulas/chemistry/high-school/43tp0p8l5e7k7aij8z38ezbwrj3r1ab028.png)
Putting values in above equation, we get:

Hence, the hydroxide ion concentration and pOH of the solution is
and 2.88 respectively