The true absorbance for a 1.0 times 10^-5 M solution is 0.7526. the percentage l
ID: 523805 • Letter: T
Question
The true absorbance for a 1.0 times 10^-5 M solution is 0.7526. the percentage light for a spectrophotometer is 0.56%, calculate the percentage by which the apparent concentration deviates from the known concentration. A transmittance of 0.3847 is measured for a 0.00023 M solution. Assuming a pathleng of 1 cm, calculate the molar absorptivity of the solute. Quinine sulfate in 0.5 M sulfuric acid is excited at 310 nm and fluoresces at 450 nm. How many Joules were dissipated through nonradiative transitions on a per molecule basis?Explanation / Answer
Absorbance (A) = log (1/transmittance(T))
Log (1/0.3847) = 0.415
According to Beer Lamberts law , A = c l
is the molar absorbtivity with units of L mol-1 cm-1
l is the path length of the sample - that is, the path length of the cuvette in which the sample is contained. We will express this measurement in centimetres.
c is the concentration of the compound in solution, expressed in mol L-1
c= 0.00023 M
= A/ c l = 0.415/ 0.00023 = 1804 L mol-1 cm-1
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