© Department of Physics, University of Guelph.

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1. Seventy five percent of the light striking a chlorophyll sample is absorbed. What is the percent transmittance and the absorbance of the sample?

2. Convert an absorbance of 0.37 to % transmittance.

3. A solution yields a %T of 48 in a sample cell with a 1.0 cm path length. What would the %T value be if the same solution were placed in a sample cell with a path length of 3.0 cm?

4. Sketch:

(a) a graph of percent transmittance versus path
length.

(b) a graph of log %T versus path length.

(Hint: Obtain expressions relating %T and pathlength in both exponential and logarithmic form.)

5.(a) You have equal volumes of two solutions
in two glass cells. Extinction coefficients and concentrations are: 4200
litre.mole^{-1}.cm^{-1} and 3.00X10^{-4}
moles/litre for solution one and 2800
litre.mole^{-1}.cm^{-1} and 2.60X10^{-4}
mole/litre for solution two. The two solutions **each** having a path
length of 1.00 cm are set one behind the other in a light beam. Find the
total absorbance of the two solutions.

(b) Equal volumes of the two solutions are mixed and some of the mixture is added to a new cell having a path length of 1.00 cm. Calculate the expected percent transmittance of the mixture. (Remember that, when you mix equal volumes, concentrations are halved.