lab 6 - Fe(NO 3 ) 3 +KSCNFe(SCN) 2+ and used a spectrometer...

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Elizabeth Farrington Experiment 6 Discussion The purpose of this lab was to learn how to use a spectrometer. We learned to measure concentrations of ions and to determine the equilibrium constant of Fe 3+ +SCN - ↔Fe(SCN) 2+ at a given temperature. For Part I we measured the absorption of a series of solutions of Fe(NO 3 ) 3 +KSCN↔Fe(SCN) 2+ using a spectrometer. From the absorption we calculated the concentration of Fe(SCN) 2+ . For A-1 it was 0, for A-2 it was 2*10 -5 , A-3=4*10 -5 , A-4=8*10 -5 , A-5=1.2*10 -4 , A- 6=1.6*10 -4 , A-7=2*10 -4 . We graphed the absorbance versus the concentration to find an equation for the calibration curve. For Part II we made solutions of
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Unformatted text preview: Fe(NO 3 ) 3 +KSCNFe(SCN) 2+ and used a spectrometer to measure the absorptions. From the equation in part I we found the concentrations of Fe(SCN) 2+ . For B-1 through B-5 respectively: 2.16*10-6 , 4.12*10-5 , 1.16*10-4 , 2.16*10-4 , 2.87*10-4 . K=[ Fe(SCN) 2+ ]/([ KSCN][ Fe(NO 3 ) 3 ]) Some possible errors would be letting the solution sit in the spectrometer so long that the light starts to affect the solution, or not being careful enough about fingerprints. I learned to use a spectrometer to measure. Next time I will work quicker to get the answers to avoid another time specific error....
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