[Whapper2006]

Using tabulated Ka and Kb values, calculate the pH of the following solutions.
Answer to 2 decimal places.

A solution containing 4.5×10-1 M HOBr and 2.4×10-1 M NaOBr.
For HOBr, Ka = 2.0×10-9.

So i have the formula pH = pKa - log ([base]/[acid])
I did -log(2.0e-9) for the pKa and got 8.7

so pH = 8.7 - log ([2.4e-1]/[4.5e-1]) and my answer was 8.97 but this turned out to be wrong.  What am I doing wrong?

[Loyal]

Using tabulated Ka and Kb values, calculate the pH of the following solutions.
Answer to 2 decimal places.

A solution containing 4.5×10-1 M HOBr and 2.4×10-1 M NaOBr.
For HOBr, Ka = 2.0×10-9.

So i have the formula pH = pKa - log ([base]/[acid])
I did -log(2.0e-9) for the pKa and got 8.7

so pH = 8.7 - log ([2.4e-1]/[4.5e-1]) and my answer was 8.97 but this turned out to be wrong.  What am I doing wrong?

Check your equation.  pH = pK_a + log([base]/[acid])

Try that and see if your answer looks better.