How to Make a Bromothymol Blue Solution

Bromothymol blue indicator will turn yellow in an acidic solution.
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Bromothymol blue solution is used as an indicator to determine the rough pH of a substance. It is prepared from a powder, household items and common laboratory chemicals that can be obtained through a scientific supply house individually or as a kit. The mixed bromothymol blue solution will turn yellow in an acidic solution and blue in basic solutions.

    Add 0.1 g of bromothymol blue powder to 10 mL of 4 percent sodium hydroxide solution in a large beaker.

    Combine 20 mL of alcohol to the sodium hydroxide/bromothymol blue solution.

    Dilute the mixture with 1 L of distilled water in a large container. The solution should be dark blue in color.

    If the solution appears green, use a pipette to slowly add sodium hydroxide drop by drop to the solution until it changes to blue.

    Things You'll Need

    • 0.1 g bromothymol blue powder
    • 10 mL 4 percent sodium hydroxide solution
    • 20 mL rubbing alcohol
    • 1 L distilled water
    • Beakers
    • Pipette
    • Stirring rod
    • Safety goggles
    • Rubber gloves

    Warnings

    • Sodium hydroxide is a corrosive chemical. Be sure to wear all safety gear, including gloves and goggles. Bromothymol blue should be prepared with scientific grade equipment in a laboratory environment.

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