Question

Consider the following equilibrium: B(aq)+H2O(l)⇌HB+(aq)+OH−(aq) Suppose that a salt of HB+ is added to a solution of B at equilibrium. Part A Will the equilibrium constant for the reaction increase, decrease, or stay the same? A. The equilibrium constant for the reaction will increase. B. The equilibrium constant for the reaction will decrease. C. The equilibrium constant for the reaction will stay the same. Part B Will the concentration of increase, decrease, or stay the same? A. The concentration of B(aq) will increase. B. The concentration of B(aq) will stay the same. C. The concentration of B(aq) will decrease. Part C Will the pH of the solution increase, decrease, or stay the same? a. The pH of the solution will increase. b. The pH of the solution will stay the same. c. The pH of the solution will decrease.

Answer 1

Answer:

Part A: C. The equilibrium constant for the reaction will stay the same.

Part B: A. The concentration of B(aq) will increase.

Part C: C. The pH of the solution will decrease.

Explanation:

• Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

Suppose that a salt of HB+ is added to a solution of B at equilibrium.

Part A Will the equilibrium constant for the reaction increase, decrease, or stay the same?

Adding HB+ will increase the concentration of the products side. so, the reaction will be shifted to the lift direction to suppress the effect of adding HB+ and attain the equilibrium again.

so, The equilibrium constant for the reaction will stay the same.

Part B Will the concentration of increase, decrease, or stay the same?

Adding HB+ will increase the concentration of the products side. so, the reaction will be shifted to the lift direction to suppress the effect of adding HB+ and attain the equilibrium again.

So, the concentration of species in the reactant sides will increase.

Thus, the right choice is:

A. The concentration of B(aq) will increase.

Part C Will the pH of the solution increase, decrease, or stay the same?

Adding HB+ will increase the concentration of the products side. so, the reaction will be shifted to the lift direction to suppress the effect of adding HB+ and attain the equilibrium again.

So, HB+ reacts with a large amount of OH- to attain the equilibrium again and shifting the reaction towards the lift side to attain the equilibrium again.

Which means decreasing the concentration of OH-.

As the concentration of OH- decreased, the pH of the solution decreased.

So, the right choice is:

c. The pH of the solution will decrease.