© 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. A sample is irradiated at its absorption
l_{max} (500 nm) with 1.00X10^{18} photons. The
absorbance of the sample was found to be 0.680. Calorimetric analysis indicated
that 0.100 joules of the incident light energy were converted into heat
in the sample. What is the approximate value of
l_{max} of the fluorescent light assuming a quantum yield
for fluorescence of 1.00? In this context, a quantum yield of 1.00 means
that for every photon absorbed one photon is fluoresced.

5. 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.)

6.(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.