Bromothymol blue

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Template:PH indicator template Bromothymol blue, also known as bromthymol blue, is a chemical indicator for weak acids and bases.

The bromothymol blue acts as a weak acid in solution and therefore can be in acid or base forms which appear yellow and blue respectively. It is green in neutral solution. Bromothymol blue is typically sold in solid form as the sodium salt of the acid indicator. It also finds occasional use in the laboratory as a biological slide stain. At this point it is already blue, and a drop or two is used on a water slide. The coverslip is placed ontop of the water droplet and the specimen in it, with the blue coloring mixed in. It is sometimes used to define cell walls or nuclei under the microscope.

Bromothymol blue can also be used to determine the presence of carbon dioxide. If the bromothymol blue turns yellow, it means that an unknown gas is carbon dioxide.

Image:Bromothymol Blue.gif

C₂₇H₂₈Br₂O₅S ↔ H⁺ + C₂₇H₂₇Br₂O₅S^-

The pKa for bromothymol blue is 7.10.

Formula: C₂₁H₁₅NaBr₂O₃S
Alternative name: Dibromothymolsulfonephthalein, BTB

Template:Organic-compound-stubde:Bromthymolblau fr:Bleu de bromothymol pl:Błękit bromotymolowy sv:Bromtymolblått