Use activity coefficients to find the concentration of hydrogen ions in a solution of 65.0 mM butanoic acid and 0.01 M NaCl. The ionization constant of butanoic acid is Ka = 1.52 × 10-5. Take the size of C3H7COO– to be 500 pm.

Question

Use activity coefficients to find the concentration of hydrogen ions in a solution of 65.0 mM butanoic acid and 0.01 M NaCl. The ionization constant of butanoic acid is Ka = 1.52 × 10-5. Take the size of C3H7COO– to be 500 pm.
Find [H+], pH, and alpha.

DrBob222 · Answer

Find the ionic strength of the solution and the activity coefficients. Use the activity coefficients to convert Ka of 1.52E-5 (the thermodynamic Ka) to K'a, the concn K for acetic butanoic acid. Then set up an ICE chart and solve for (H^+). Post your work if you get stuck and need more assistance.