Does anyone know what the chemical reaction is between Phenolphthalein, sodium hydroxide and sulfuric acid?

The formula for phenolphthalein is complicated, so let's call it HA. HA is a white powder that dissolves in alcohol/water to give a water-white solution. If you add NaOH to this solution, then HA + NaOH ===> Na+ + A- + H2O, where A- is red. Then, if you add H2SO4 to the solution, H2SO4 + A- ===> HA + HSO4-, and you get a water-white solution again.