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Is bromothymol blue or phenolphthalein a better indicator?
Bromothymol blue is the best of the three indicators for this titration. For the weak acid, the methyl orange color change will occur long before the equivalence point, the bromothymol blue change is slightly premature, and phenolphthalein color change occurs close to the correct place (around pH 8.9).
What is bromothymol blue and indicator for?
Bromothymol blue is a pH indicator for weak acids and bases. In neutral solution, it appears bluish-green. At pH above 7.6 it appears blue, and at pH below 6.0 it appears yellow. Bromothymol blue (BTB) is an anionic dye. It can be protonated or deprotonated to generate yellow or blue.
What indicator can be used instead of bromothymol blue?
Indicator Range
| Indicator | Colour | pH range |
|---|---|---|
| Methyl Orange | red | 3.2 – 4.4 |
| Bromocresol Green | yellow | 3.8 – 5.4 |
| Methyl Red | yellow | 4.8 – 6.0 |
| Bromothymol Blue | yellow | 6.0 – 7.6 |
What makes a good indicator for titration?
When selecting an indicator for acid-base titrations, choose an indicator whose pH range falls within the pH change of the reaction. The indicator phenolphthalein, whose range spans from pH 8 to 10, therefore makes a good choice for this type of titration.
What is a better indicator than phenolphthalein?
Problem Solving: Choosing an Acid-Base Indicator for a Titration
| Indicator name | pH Range | Colour change (low pH → high pH) |
|---|---|---|
| methyl orange | 3.1 – 4.4 | red → yellow |
| bromothymol blue | 6.0 – 7.6 | yellow → blue |
| phenolphthalein | 8.3 – 10.0 | colourless → pink |
Why did the color of the bromothymol blue change?
What caused the bromothymol blue solution to change color? The bromothymol blue solution changed color because there was a chemical reaction with the carbon dioxide. After the exercising the bromothymol blue turned green faster. This is because the carbon dioxide was expelled into it faster, because of the exercising.
Why is litmus paper not a very good indicator?
The litmus test is quick and simple, but it suffers from a few limitations. First, it’s not an accurate indicator of pH; it does not yield a numerical pH value. Instead, it roughly indicates whether a sample is an acid or a base. Second, the paper can change colors for other reasons besides an acid-base reaction.
Can bromothymol blue be called an acid base indicator?
Because of the weak acid produced by carbon dioxide, we can detect its presence by using an acid-base indicator called bromothymol blue . Bromothymol blue (or BTB for short) is blue in a solution with a pH of 7 or above. The solution will turn to a green color when the pH falls below 7 and then to a yellow color.
Why is bromothymol blue called Blue?
Bromothymol is used in obstetrics for detecting premature rupture of membranes. Amniotic fluid typically has a pH > 7.2, bromothymol will therefore turn blue when brought in contact with fluid leaking from the amnion. As vaginal pH normally is acidic, the blue color indicates the presence of amniotic fluid.
What does bromothymol blue stand for?
Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). A common use is for measuring the presence of carbonic acid in a liquid.
What does the color for bromothymol blue indicate?
Bromthymol blue changes color over a pH range from 6.0 (yellow) to 7.6 (blue). It is a good indicator of dissolved carbon dioxide (CO 2) and other weakly acidic solutions. Despite its name, bromothymol blue solution may sometimes appear yellow or reddish depending on the pH of the stock water used to prepare this pH indicator solution.