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Assuming a pKa of 7.1 for bromothymol blue, over what range will it be an effective...

Assuming a pKa of 7.1 for bromothymol blue, over what range will it be an effective acib-base indicator. Show the calculations you used to determine this range

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Answer #1

Bromothymol blue is an indicator, which is used to show acid base behaviour with different colors. It shows Yellow color at deprotonated form(acidic form) with pH 6.0 and blue with protonated form with pH of 7.6 with mid range green color.

As the information is insufficient for this question, the absorbance of yellow and blue occurs at green at 616 nm and yellow at 453 nm.

Equilibrium constant(K) = [H+] * (Agreen - Ayellow) * Ayellow/(Agreen-Ablue)*Ablue

Since absorbance data is not mentioned, so we can't calculate the final range. But pH will be calculated using the sodium phosphate buffer solution at a point where absorbance is maximum. It will give the range

Regards

Nimish

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