Enough of a monoprotic acid is dissolved in water to produce a 0.0165 M solution. The pH of the resulting solution is 2.38. Calculate the Ka for the acid.

Answer 1

Nevermind I figured it out,
With the equation
Ka = x^2 / 0.0165 - x

x = [H+]
I forgot to do the 0.0165-x in my original calculation, but after doing that I got the correct answer.

Answer 2

That's right. 0.0165-x can't be assumed = 0.0165