Pipet 10 mL of standardized 0.1 M HCl into the flask and swirl. Heat the solution to a gentle boil and maintain the heat for 1 minute to remove dissolved carbon dioxide. Add 4-8 drops of bromophenol blue indicator, which is yellow in acidic solution and blue in basic solution. If the solution is blue, pipet an additional 10.00 mL of 0.1 M HCl into the solution and boil again. Repeat as often as necessary.