could the equation - pH=pKa+log([A]/[HA]) - be applied for the case of strong acid? Although the percentage of dissociation of strong acid/base is very high, there still exists a equilibrium, right? secondly, if i tried to explain the resistance in pH of buffer *in terms of* the above equation, then the pH of a buffer will depend only on the ratio of [A]/[HA]; then for both strong/weak acid with its salt, if i add H+ to each solution, the result will be: [A] decrease; [HA] increase (both cases). then how can i explain the difference that weak acid buffer has the ability to resist change in pH? Please help me to solve this query, thanks a lot!!!!!!