Final answer:
The pH of a 7.5 × 10-3 M Ba(OH)2 solution at 25°C is 2.42, which is not provided as an option.
Step-by-step explanation:
The pH of a solution can be calculated using the equation pH = -log[H+]. In this case, we need to find the concentration of hydronium ion (H+) in the solution. Since Ba(OH)2 ionizes completely, it will produce 2 hydroxide ions (OH-) for every 1 Ba(OH)2 molecule.
Therefore, the concentration of hydronium ion (H+) is half the concentration of hydroxide ions (OH-), which is 7.5 × 10-3 / 2 = 3.75 × 10-3 M. Taking the negative logarithm of this concentration gives the pH: pH = -log(3.75 × 10-3) = 2.42. Therefore, the correct answer is none of the options provided.