posted by amanda1012 .
Use activity coefficients to find the concentration of hydrogen ions in a solution of 70.0 mM butanoic acid and 0.1 M NaCl. The ionization constant of butanoic acid is Ka = 1.52 × 10-5. Take the size of C3H7COO– to be 500 pm.
How much of this do you know how to do? Have you calculated the ionic strength of the solution? Have you calculated the activity coefficient(s)?
My biggest problem is knowing where to start. So I calculate the ionic strength then the activity coefficients. Then do I just "plug and chug"
Yes, more or less. You calculate u (ionic strength) first and use that to calculate activity coefficient. Using activity coefficient correct the Ka for butanoic acid, then plug and chug.