Question

How would a decrease in pH affect the equilibrium position of the following acid-base reaction: HA + B ↔ A- + HB+ Assuming other conditions remain constant, predict the direction in which the equilibrium will shift and explain your reasoning.

Answer 1

A decrease in pH indicates an increase in the concentration of H+ ions in the solution. According to Le Chatelier's principle, when a system at equilibrium experiences a change in concentration, temperature, or pressure, the system will shift its equilibrium position to counteract the change.In this case, the increase in H+ ions will cause the equilibrium to shift in the direction that consumes the excess H+ ions. The reaction can be rewritten as:HA + B  A- + H+ + B+ Now, it is clear that the increase in H+ ions will cause the equilibrium to shift to the left, favoring the formation of HA and B. This is because the reaction will try to consume the excess H+ ions by forming more HA and B, thus counteracting the change in pH.