5. (40 pts) Bromothymol blue (BTB) is a pH indicator with exhibiting different colors depending on its protonation level

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5 40 Pts Bromothymol Blue Btb Is A Ph Indicator With Exhibiting Different Colors Depending On Its Protonation Level 1 (51.53 KiB) Viewed 19 times

5. (40 pts) Bromothymol blue (BTB) is a pH indicator with exhibiting different colors depending on its protonation level at different pH. The following table is the absorption of 0.2% (w/v) BTB solution at 620 nm that corresponds to the maximum absorption peak of deprotonated form of BTB. Mw of BTB is 624.38 g-mol-1. At pH 8, calculate the molar concentrations of BTB and deprotonated BTB. You need to first find pKa of BTB. 10 11 pH A(620 nm) 3 4 5 6 7 8 9 0 0 0.2 0.5 2.0 3.5 3.7 4 4