They would both appearyellow. 1 decade ago. PubChem Substance ID 24892083. Ensure that the solutions are mixed well. Solutions of different concentration of the indicator were used. Assume a cuvet with a 14.45 mm diameter was used. EC Number 252-169-7. It shows that pH=pKa where [ln-]= [Hln] or hwere ( [ln-]/ [Hln])=1 or where log ( [ln-]/ [Hln])=0. Anonymous. Bromothymol blue, Powder ACS. NACRES NA.47 There is a linear relationship between log ( [ln-]/ [Hln]) and pH. pH = pKa - log ( [HIn] / [In-] ) … (2) Chloroform showed the highest affinity for bromothymol blue, followed by methylene chloride, ethylene dichloride, benzene, toluene, and carbon tetrachloride. 2 Answers. Empirical Formula (Hill Notation) C 27 H 27 Br 2 NaO 5 S . [10] [11] describe multiwavelength analysis and nonlinear least squares regres-sion methods. The pKa can be determined from the spectrophotometric data using different methods. Beilstein/REAXYS Number 6887926 . For this reason it can be electrostatically immobilized on the surface on anion-exchanger resin like Amberlite IRA 401. Other indicators work in different pH ranges. In this experiment, spectrophotometry is employed to measure the pKa of bromothymol blue, an acid-base indicator. Meloun et al. Place three small drops of bromothymol blue solution into each of the 5 cuvettes. Explain why the acid - base indicator bromothymol blue turns yellow when added to dilute HCl but blue when added to dilute NaOH. Spectrophotometric determination of the pKa of Bromothymol Blue. Bromothymol blue is an acidic pH chromoionophore where acid to base change corresponds to its neutral to anionic form, respectively. The pKa′ value was determined using a method similar to that of Reilley and Swayer. As a pH indicator,bromothymol blue, for example, would be useful between from about pH6.0 to pH 7.6. 7.1) that is used as a biological slide vital stain to define cell walls or nuclei under the mic... SDS. Using bromothymol blue you wouldn't be able to distinquish between anacid with pH 4 from an acid with pH 5. Relevance. 2. MDL number MFCD00077263. Determination of the pK_a of Bromothymol Blue Use the following graph to determine the molar absorptivity of Bromothymol blue (BTB)? Computational methods, such as SQUAD (84) 16 and SPECFIT/32, and some new methods The indicator (HIn) is a monoprotic acid and we can represent its dissociation as follows: HIn → H+ + In- … (1) The equilibrium expression for such dissociation can be written as. Favorite Answer. ,IC10113005EA,IC10113025EA. Given the equation: y= 48048x- 0.0105, find the molar absorptivity and use this value in your experiment. Answer Save. Indicator: pH Range: pKa: Acid Form: Base Form: Methy Violet: 0.0 - 1.6: 0.8: Yellow: Blue: Thymol Blue: 1.2 - 2.8: 1.6: Red: Yellow: Methyl Yellow: 29. Supplier: MP Biomedicals. Description: Bromothymol Blue (BTB) is a pH indicator (pKa approx. 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