Question

what is the ph change of a 0.270 m solution of citric acid ( pka=4.77 ) if 0.170 m citrate is added with no change in volume?

Answer 1

Adding citrate to a solution of citric acid will not change the pH.

Step-by-step explanation:

Citric acid is a weak acid, and when it dissolves in water, it partially dissociates into citrate ions and hydrogen ions. The pH of a solution depends on the concentration of hydrogen ions. Adding more citrate ions to the solution will not affect the concentration of hydrogen ions. Therefore, the pH of the solution will remain the same.

Answer 2

To calculate the pH change when 0.170 M citrate is added to a 0.270 M solution of citric acid, we can use the acid dissociation equilibrium of citric acid. By considering the Ka value and the concentration of H+ ions, we can calculate the pH change using the formula [H+] = [H+] initial + [Citrate-] added.

Step-by-step explanation:

pH Change Calculation:

Citric acid is a weak acid and when it dissolves in water, it releases H+ ions, contributing to the acidic pH of the solution. The pH of a solution is determined by the concentration of H+ ions.

To calculate the pH change when 0.170 M citrate is added to a 0.270 M solution of citric acid, we need to consider the acid dissociation equilibrium of citric acid:

Citric Acid <--> H+ + Citrate-

The Ka of citric acid is given as 4.77. From the Ka expression, we can calculate the concentration of H+ ions:

Ka = [H+][Citrate-] / [Citric Acid]

Since the volume of the solution does not change, the number of moles of citrate added will equal the number of moles of H+ ions produced. Therefore, the final concentration of H+ ions will be:

[H+] = [H+] initial + [Citrate-] added

Substituting the values, we can calculate the pH change.