- Bromothymol blue
chembox new
ImageFile=Bromothymol-blue-2D-skeletal.png
OtherNames=
Section1=Chembox Identifiers
CASNo=76-59-5
PubChem=6450
SMILES=CC1=C(C(=C(C=C1C2(C3=CC=CC=C3S(=O)(=O)O2)C4=CC(=C(C(=C4C)Br)O)C(C)C)C(C)C)O)Br
Section2=Chembox Properties
C=27|H=28|Br=2|O=5|S=1
Appearance=
Density=1.25 g/cm3
MeltingPtC=202
BoilingPt=
Solubility=
pKa = 7.10
Section3=Chembox Hazards
MainHazards=
FlashPt=
Autoignition=Bromothymol Blue (also known as dibromothymolsulfonephthalein, Bromthymol Blue, and BTB) is a chemical indicator for weak acids and bases. The chemical is also used for observing photosynthetic activities or respiratory indicators (turns yellow as CO2 is added).
Bromothymol Blue acts as a weak acid in solution. It can thus be in protonated or deprotonated form, appearing yellow and blue respectively. It is green in neutral solution. It 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. Thecover slip is placed on top 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 is mostly used in measuring substances that would have relatively low acidic or basic levels (near a neutral pH). It is often used in managing the pH of pools and fish tanks, and for measuring the presence of
carbonic acid in a liquid.A common demonstration of BTB's pH indicator properties involves exhaling through a tube into a neutral solution of BTB. As
carbon dioxide is absorbed from the breath into the solution, formingcarbonic acid , the solution changes color from green to yellow.Bromothymol is also used in Obstetrics for detecting premature rupture of membranes.
The
pKa for bromothymol blue is 7.10.Indicator colors
ee also
*
Phenolphthalein External links
* [http://www.jtbaker.com/msds/englishhtml/b5380.htm J.T.Baker MSDS]
* [http://www.sigmaaldrich.com/catalog/search/ProductDetail/RIEDEL/32774 Bromothymol Blue (Sodium Salt) -Sigma Aldrich]
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