[chanelo]

The question asks for the pH of 80.0 mL of a solution containing 0.23 M IO^- and 0.45 M HIO. The Ka for HIO is 2.3 x 10^-11.

So I did:
pH = 2.3 x 10^-11 + log (0.0184 mol/L IO^- / 0.036 mol/L HIO)
pH = -0.29
Is this right? I'm not sure if a negative pH is possible but I can't see what I did wrong.

[AWK]

You forgot about the square root.

[Borek]

pH = 2.3 x 10^-11 + log (0.0184 mol/L IO^- / 0.036 mol/L HIO)
pH = -0.29
Is this right? I'm not sure if a negative pH is possible but I can't see what I did wrong.

You forgot about the square root.

No idea what square root AWK is talking about, my bet is he meant log. Your first equation is based on pKa, not on Ka.

[chanelo]

Thanks Borek, I can't believe I missed that! I got 10.35 after converting Ka into pKa, which makes a lot more sense.