Titrations

Flasks of different colors

Think IconIndicators are used in titration solutions to signal the completion of the acid-base reaction. Did you know that the indicators are generally clear, but as the solution of known concentration is added using a burette, the solution in question will change colors? Different indicators are used for different pH ranges. Take a moment to view the table that contains several different commonly use indicators.

Indicator
End Point Color in the Presence of Acid
End Point Color in the Presence of Base
pH Range
Thymol Blue Red Yellow 1.2-1.8
Methyl Orange Red Yellow 3.2-4.4
Bromocresol Green Yellow Blue 3.8-5.4
Methyl Red Yellow Red 4.8-6.0
Bromothymol Blue Yellow Red 6.8-8.4
Thymol Blye Yellow Blue 8.0-9.6
Phenolphtalein Colorless Pink 8.2-10.0