Question

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.

Answer 1

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)?

Answer 2

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"

Answer 3

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.

Answer 4

Thank you!