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Using the values of the effective molar absorptivities you determined from your

ID: 1059133 • Letter: U

Question

Using the values of the effective molar absorptivities you determined from your slopes and the values of the absorption you obtained for the mixture at the spectral maxima of 434 nm and 618 nm, solve the 2x2 simultaneous linear equations for the concentrations of bromothymol blue and thymol blue.

The slope of thymol blue at 434nm is y=.0124x, and bromothymol blue at 434nm is y=.0053x.

The slope of thymol at 618nm is y=.0018x, and bromothymol blue at 618nm is y=.0296x.

Given that the absorbance of the unknown mixture is 0.524 at 434nm and 0.293 at 618nm, what is the concentration of bromothymol blue and thymol blue respectively?

Additionally, the undiluted molarity of the thymol is 61.6um and the molarity of the undiluted bromothymol blue is 23.2um.

Explanation / Answer

given ar 434 nm, for thymol blude Ab= 0.0124 and for bromothymol blue =0.0053

at 618 Ab= 0.0018 for thymol blue and for bromothymol blue = 0.0296

let c1 =concentration of bromothymol blue and c2= concentration of thymol blue

c1*0.0053+c2*0.124= 0.524 (1) divide by 0.0053 c1+23. 4c2 = 99 (1A) and c1*0.0296+c2*0.0018= 0.293 (2), divided by 0.0296 , c1+0.061c2= 9.9

Eq. 1A- Eq.2A = c2*(23.4- 0.061)= 99-9.9=89.1, c2= 3.8uM and from Eq.1A, c1+23.4*3.8= 99, c1=10.08 um