2lab5 - Jessica Gaboriault Lab Partner Jacki Lerea Lab...

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Unformatted text preview: Jessica Gaboriault Lab Partner: Jacki Lerea 3/25/08 Lab Section A, Tuesday at 2pm Hutch 115 Experiment 5: Spectroscopy of atoms and molecules Purpose: The purpose in this experiment is to measure and analyze the emission spectrum for Hydrogen (H), mercury (Hg), sodium (Na), and the incandescent bulb. We will also measure and analyze absorption spectra in organic molecules: Ph - CH = CH – Ph (1 double bond) Ph – CH – CH – CH = CH – Ph (2 double bonds) Ph – CH = CH – CH = CH – CH = CH – Ph (3 double bonds) Ph – CH = CH – CH = CH – CH = CH – CH = CH – Ph (4 double bonds) Procedure : see pages 37-50 in the lab manual. Points to note: 1.5 x 10-4 M concentration of molecules- Rinse with ethanol- Pg. 49, point 5- Print spectra, one copy- Pg. 48 safety- Blank cuvette is ethanol- A = E l c- A = 0.3 to 1.3 or 0.2 to 0.8 (beer’s law), try to get 0.8 absorbance- M 1 V 1 = M 2 V 2 dilution equation- M 1 = 1.5 x 10-4 M (stock solution) Data and Observations : Part 1: Emission Spectrum Mercury Length (cm) Color 74.5 Dark blue 78.0 Blue/green 81 Fluorescent green 84 Fluorescent orange/yellow 86 Neon red 85 Orange Sodium Length (cm) Color 76.2 Blue 78 Green/turquoise 79 Light green 82.5 Yellow 83.5 Bright orange 85 red Hydrogen Length (cm) Color 75 Dark blue/violet 78 Sky blue 79.5 red Incandescent lamp Length (cm) Color 73-75 Purple 75-78 Blue 78-81 Green 81-84 Yellow/orange 84-88 red Calculations : Part 2: Organic Molecules Given: values for trans-stilbene: 2.5 x 10 Є 4 L/mol cm Diphenylbutadiene: 5.0 x 10 4 L/mol cm Diphenyloctatetraene: 1.0 x 10 5 L/mol cm To find value for diphenylhexatriene, average (1.0 x 10 є 5 L/mol cm) * (5.0 x 10 4 L/mol cm) / 2 = 7.5 x 10 4 L/mol cm Organic molecule # of double bonds values Є trans-stilbene 1 2.5 x 10 4 L/mol cm Diphenylbutadiene 2 5.0 x 10 4 L/mol cm diphenylhexatriene 3 7.5 x 10 4 L/mol cm Diphenyloctatetraene 4 1.0 x 10 5 L/mol cm To find concentration :- We wanted to obtain an absorbance of 0.8, so we used 0.8 as AWe wanted to obtain an absorbance of 0....
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This note was uploaded on 02/13/2010 for the course CHM 29294 taught by Professor Krugh during the Fall '10 term at Rochester.

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2lab5 - Jessica Gaboriault Lab Partner Jacki Lerea Lab...

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