Acetic acid, HC2H3O2 is monoprotic. A 0.010M solution of lactic acid has a pH 2.44. calculate the ionization constant, Ka, for this acid.
Let's call lactic acid, HC3H5O3, HL make things easier to type.
Then pH = -log (H^+).
If pH is 2.44 then (H^+) = ? My calculator is broken so you will need to do this part yourself. Let's say the answer is 1E-3 but that isn't the answer.
..................HL ==> H^+ + L^-
I...............0.010M......0.......0
C..............-x...............x.......x
E...........0.010-x.........x........x
Ka = (H^+)(L^-)/(HL)
Ka = (x)(x)/(0.010-x)
Now substitute the value of x you get from above into the Ka expression and calculate Ka. Post your work if you get stuck.