Question

What do I do for this question? calculate the stray light percentage of a spectrophotometer if the measured concentration of a sample is 1.18x10^-5 M. the sample's molar absorptivity is 2.0x10^4 M mol^-1 cm^-1, its concentration is 1.20x10^-5 M, and the thickness of the cuvette is 1.000cm.

Answer 1

we have to find the percent absorbance of light by sample.

Measured Concentration = 1.18*10^-5M

Molar absorptivity () = 2.0*10⁴ M/ mol.cm

Concentration (l) = 1.00 cm

Actual concentration = 1.20 *10^-5 M

Now, Absorbance(A) = *C*l

At C = 1.18*10^-5M

A = 1.18*10^-5M*2.0*10⁴ M/ mol.cm*1.00 cm = 0.236 mol/L²

At C = 1.20 *10^-5 M

A = 1.20 *10^-5 M*2.0*10⁴ M/ mol.cm*1.00 cm = 0.24 mol/L²

Thus, stray light percentage = (Absorbance at measured concentration/ Absorbance at actual)concentration*100% = (0.236/0.24)*100% = 98.3 %