a solution is prepared by dissolving 02.50 mole of Ba(OH)2 in enough water to get 4.00 L of solution. What are the OH- and H3O+ molar concentrations?

To determine the OH- and H3O+ molar concentrations in the solution, we need to understand that Ba(OH)2 is a strong base and dissociates completely in water. The balanced chemical equation for the dissociation of Ba(OH)2 is:

Ba(OH)2 (aq) → Ba2+ (aq) + 2 OH- (aq)

From the equation, we can see that for every one mole of Ba(OH)2 that dissociates, we get two moles of OH- ions. Therefore, the number of moles of OH- ions in the solution will be twice the number of moles of Ba(OH)2 used.

Given that the solution contains 0.50 mole of Ba(OH)2, the number of moles of OH- ions present will be:

0.50 mole Ba(OH)2 × 2 mole OH-/1 mole Ba(OH)2 = 1.00 mole OH-

Next, we need to calculate the molar concentration of OH-. Molar concentration (also known as molarity) is defined as moles of solute divided by the volume of the solution in liters. In this case, the volume of the solution is given as 4.00 L.

The molar concentration of OH- ions is therefore:

Concentration of OH- = moles of OH- / volume of solution
Concentration of OH- = 1.00 mole / 4.00 L = 0.25 M

Hence, the molar concentration of OH- ions in the solution is 0.25 M.

Regarding H3O+ ions, it's important to note that Ba(OH)2 is a base and not an acid. Therefore, the concentration of H3O+ ions in the solution will be negligible unless there are other acidic species present.

In summary, the molar concentration of OH- ions in the solution is 0.25 M, while the molar concentration of H3O+ ions will be negligible.