HANDS-ON APPROACH TO VISIBLE SPECTROMETRY Project number: SI/03/B/F/PP-176012 © FKKT, Ljubljana, 2003-2005 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

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

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

Some examples of slides

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?

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

Observations yellow foil violet foil

LED selection for measuring transmittance filter foils

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

Measuring transmittance with SpektraTM http://www.ntfkii.uni-lj.si/analchemvoc/slo/spektra/measuringprocedure.htm

Measurement of transmittance of solutions Dispensing drops into a blister

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)

Example of calibration line for determining salicylate

Result Chemical equilibrium - Le Chatelier’s Principle Experiment 13 3 Fe3+ + 6 CH3COO- + 4 H2O [Fe3(OH)2(CH3COO)6]+ + 2 H3O+ Experiment 13

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.