1. The problem statement, all variables and given/known data What is the H3O+ concentration of a 0.100 M acetic acid solution (Ka = 1.8 x 10-5)? a. 1.8 x 10-5 b. 1.8 x 10-4 c. 1.3 x 10-2 d. 1.3 x 10-3 e. 0.9 x 10-3 2. Relevant equations 3. The attempt at a solution so the question is supposed to be D. but I thought that The Ka tells the concentration of the H3O+!! Doesn't it ?! I think you're supposed to take the square root of 1.8 x 10-5 the multiply it by 0.1 BUT WHY?! thanks in advance!