EDTA is a weak acid, which means that it partially dissociates in water to form H+ ions (protons) and EDTA- ions. The pH of a solution is determined by the concentration of H+ ions, with a lower pH indicating a higher concentration of H+ ions and a higher pH indicating a lower concentration of H+ ions.
If you add HCl to the solution, you will be adding more H+ ions, which will cause the pH to decrease. Therefore, adding HCl would move the pH further away from the desired pH of 8.0.
On the other hand, if you add NaOH to the solution, you will be adding OH- ions, which will react with the H+ ions to form water molecules. This will reduce the concentration of H+ ions and increase the pH. By carefully adding NaOH, you can reach the desired pH of 8.0.
