Consider the equilibrium $$ \mathrm{B}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{HB}^{+}(a q)+\mathrm{OH}^{-}(a q) $$ Suppose that a salt of \(\mathrm{HB}^{+}(a q)\) is added to a solution of \(\mathrm{B}(a q)\) at equilibrium. (a) Will the equilibrium constant for the reaction increase, decrease, or stay the same? (b) Will the concentration of \(\mathrm{B}(a q)\) increase, decrease, or stay the same? (c) Will the pH of the solution increase, decrease, or stay the same?

When analyzing a reaction in equilibrium and determining the effect of adding a reactant or a product, it is crucial to consider the Le Châtelier's principle. According to this principle, if a system at equilibrium is subjected to a change in concentration, temperature, or volume, the equilibrium will shift in a direction that counteracts the applied change to regain equilibrium. Let's consider the addition of HB+(aq) salt in our reaction. Remember that the equilibrium constant, K, only changes if there is a change in temperature. Since there is no mention of a change in temperature, we can conclude that the equilibrium constant will remain the same. Answer: (a) The equilibrium constant, K, will stay the same.

Since we are adding HB+(aq) to the solution, the concentration of HB+ will increase, according to Le Châtelier's principle, the equilibrium will shift to the left to counteract this change. As the equilibrium shifts to the left, the concentration of B(aq) will increase. Answer: (b) The concentration of B(aq) will increase.

In this reaction, the equilibrium is shifted towards the left when the concentration of HB+ is increased. As the concentration of B(aq) increases, the concentration of OH- ions would decrease since the reaction is moving to the left. A decrease in the concentration of OH- ions will lead to an increase in H+ ions concentration. Therefore, the pH will decrease. Recall the relationship between pH and [H+]: \[ pH = -\log[H+] \] As the concentration of H+ ions increases, the pH value will decrease. Answer: (c) The pH of the solution will decrease.