Calculate the pH and pOH of a 0.00002M solution of acetic acid.

Call acetic acid HAc.

............HAc ==> H^+ + Ac^-
initial..2E-5M......0.......0
change....-x........x........x
equil...2E-5-x......x........x

Ka = (H^+)(Ac^-)/(HAc)
Substitute and solve for H^+, then
pH = -log(H^+).
Then pH + pOH = pKw = 14
Youknow pH and pKw, solve for pOH.

Note: I think you must solve the quadratic; i.e., you will not be able to make simplifying assumptions.