Final answer:
To find the hydronium ion concentration from a pOH of 12.8, subtract pOH from 14 to get pH, then calculate 10 to the power of the negative pH. The concentration of H3O+ is 6.31 × 10^-2 M, indicating a basic solution.
Step-by-step explanation:
To calculate the concentration of H3O+ in a solution with a pOH of 12.8, you first need to understand the relationship between pH, pOH, and the concentrations of H3O+ and OH- in a solution. The formula pH + pOH = 14 is used at 25 °C, which is standard temperature for these calculations.
Given that the pOH is 12.8, we can calculate the pH:
pH = 14 - pOH
pH = 14 - 12.8
pH = 1.2
Now, knowing the pH, we can find the hydronium ion concentration by using the formula:
[H3O+] = 10-pH
[H3O+] = 10-1.2
Using a calculator, you would calculate the hydronium ion concentration to be approximately 6.31 × 10-2 M. This indicates that the solution is basic because a pOH greater than 7 signifies a basic solution, and consequently, a pH less than 7 also confirms it.