Final answer:
The [OH⁻] for a 0.010 M Ba(OH)₂ solution, multiply the concentration by 2 due to two hydroxide ions per unit, resulting in 0.020 M. To find pH, take the negative logarithm of the [H₃O⁺] concentration, which for this solution equals 12.30.
Step-by-step explanation:
The subject of the question is the calculation of hydroxide ion concentration ([OH⁻]) and pH of a barium hydroxide (Ba(OH)₂) solution in chemistry. This involves the use of dissociation principles for strong bases, the self-ionization constant of water (Kw), and the pOH scale.
Barium hydroxide is a strong base that fully dissociates in water, releasing two hydroxide ions per formula unit. Thus, the concentration of [OH⁻] in a 0.010 M Ba(OH)₂ solution is actually 0.020 M. The formula to relate [OH⁻] and [H3O⁻] is: [H3O⁻] = Kw / [OH⁻], where Kw is the ion-product constant for water, which is 1.0 x 10⁻⁺ at 25°C. Substituting the given values, we find [H3O⁻] = 1.0 x 10⁻⁺ / 0.020 M = 5.0 x 10⁻⁹M.
Next, we calculate the pH from the [H3O⁻] by taking the negative logarithm: pH = − log [H3O⁻]. So, the pH of the solution is − log(5.0 x 10⁻⁹) which equals 12.30.