1. HANDS-ON APPROACH TO VISIBLE SPECTROMETRY
Project number: SI/03/B/F/PP
© FKKT, Ljubljana,
HANDS-ON APPROACH
TO VISIBLE SPECTROMETRY
Nataša Gros1, Margareta Vrtačnik2, M. Filomena Camões3
1 Faculty of Chemistry and Chemical Technology,
2 Faculty of Natural Sciences and Engineering,
University of Ljubljana, Slovenia
3 University of Lisbon, Portugal

2. LEGEND Video clip Experiment Task in the Workbook
Navigation – next module
Navigation – back to modules

3. MODULES 1. Light as radiation 2. Light and colour perception
3. Colour of substances and light transmittance
4. Colour, absorption spectrum and colour of a substance
5. Measurement of light transmittance
6. Spectrometric determination of concentration
7. Practical application of visible spectrometry
8. Visible spectrometry as a means for better comprehension
of fundamental chemical concepts
A Chemical equilibrium
B Chemical kinetics

4. Some examples of slides

5. Additive mixing of colours: green and blue
Turn on the knobs for blue, green and red LEDs
to their far left-hand position.
Task 1
Workbook
Switch on the green LED.
Turn the knob of the green LED to its medium position.
Switch on the blue LED and start increasing the itensity of the blue light.
After the blue LED has reached maximum intensity, start decreasing
the intensity of the green LED.
At the end of the experiment switch off the green LED and check that the knob
is to its far left-hand position.
What colours have you observed during this experiment?

6. Principle
Workbook
combine
In additive mixing we __________ beams of light of
__________ colours. Red, green and blue are _________ colours
for our _________ perception. By __________ them in appropriate
_________ we can obtain all other __________.
basic
different
mixing
visual
proportion
colours

7. Observations
yellow foil
violet foil

8. LED selection for measuring transmittance
filter foils

9. T = T transmittance Фo Ф Ф Фo Фo Ф
Definition of transmittance Фo Ф Ф
T = Фo Фo Ф
Фo power of radiation incident on the absorption medium
Ф power of radiation transmitted by the absorption medium
T transmittance

10. Measuring transmittance with SpektraTM

11. Measurement of transmittance of solutions
Dispensing drops into a blister

12. Calibration solution number
Determination of salicylate by the method of
the calibration line
Workbook
Experiment 13
Blank
Calibration solution number
Sample 1 2 3 4 5 6 7
Salicylate (aq) (S) -
Fe(NO3)3 (aq) (S)
H2O (S) 8
Sample (S)

13. Example of calibration line for determining salicylate

14. Result Chemical equilibrium - Le Chatelier’s Principle Experiment 13
3 Fe CH3COO H2O [Fe3(OH)2(CH3COO)6] H3O+
Experiment 13

15. Acknowledgements
This Project was supported by the European Community funds.
The content does not reflect the opinion of the
European Union, or the National Agency.
For this reason neither the National Agency nor the
European Union take any
responsibility regarding the content of the report.