STUDY GUIDE 6, SELF TEST 1

© Department of Physics, University of Guelph.

Click on the problem or part you wish.

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.