Part III. Ammonia is a weak base and establishes the following equilibrium in water:
NH3(aq) + H2O(l) NH4+(aq) + OH-(aq).
In Part III, the phenolphthalein indicator is used to monitor the equilibrium shifts of the ammonia/ammonium ion system.
The phenolphthalein equilibrium established with water is
Hph(aq)(colorless) + H2O (l) H3O+ (aq) + ph-(aq)(pink or red).
You compared the color of the solutions in three test tubes that initially contained 3 mL of 0.1 M ammonium hydroxide and a few drops of phenolphthalein indicator. In the first test tube, you added 1 M NH4Cl dropwise.
What color change was observed and what did this color change indicate about the shift in the phenolphthalein equilibrium?