Lab 7 Report Part 1 PDF

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Lab 7 Report Part 1...

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Hieu Pham Lab 7 Report : Absorption Spectrum of a Conjugated Dye - Part 1

28. 1,1’-diethyl-4,4’-cyanine iodide: L = 5* 154 nm + 3*134 nm = 1172 nm ( 5 single bonds, 3 double bonds) 1,1’-diethyl-4,4’-carbocyanine: L = 5*154 nm + 5*134 nm = 1440 nm ( 5 single bonds, 5 double bonds) 1,1’-diethyl-4,4’-dicarbocyanine iodide: L = 7*154 nm + 5*134 nm = 1748 nm (5 single bonds, 5 double bonds)

29. a. 1,1’-diethyl-4,4’-cyanine iodide: N ( number of delocalized electron ) = 10 1,1’-diethyl-4,4’-carbocyanine: N = 12 1,1’-diethyl-4,4’-dicarbocyanine iodide: N = 14 b. - 1,1’-diethyl-4,4’-cyanine iodide: λmax = 8mcL2/h(N+1) L = (626 nm* 6.626*10-34 (m2.kg/s)*(10+1)/8*9.1*10-31 (kg)*3*108 (m/s))1/2 = 1.445 nm = 14.450 A -

1,1’-diethyl-4,4’-carbocyanine: λmax = 8mcL2/h(N+1)

L = (727 nm* 6.626*10-34 (m2.kg/s)*(12+1)/8*9.1*10-31 (kg)*3*108 (m/s))1/2 = 1.693 nm = 16.930 A -

1,1’-diethyl-4,4’-dicarbocyanine iodide

L = (850 nm* 6.626*10-34 (m2.kg/s)*(14+1)/8*9.1*10-31 (kg)*3*108 (m/s))1/2 = 1.967 nm = 19.670 A

dye 1,1’-diethyl-4,4’cyanine iodide 1,1’-diethyl-4,4’carbocyanine 1,1’-diethyl-4,4’dicarbocyanine iodide

λmax 626 nm

N 10

L (nm) 1.445 nm

L (A) 14.445 A

727 nm

12

1693 nm

16.930 A

850 nm

14

1.967 nm

19.670 A

30. The results from 28 and 29 slightly agree to each other. This shows the difference between 2 methods. However, in general, the larger the molecule is, the longer the length of the conjugated chain, as the more numbers of delocalized electrons.

31.

From the graph, the average C-C bond is determined to be 0.1669 nm

32. λmax/ 5 (nm) 125.2 145.4 170.0

L (nm) 0.646 nm 0.757 nm 0.879 nm

L (A) 6.46 A 7.57 A 8.79 A

N 10 12 14

Therefor the C-C bond has the average length of 0.0584 nm from this analysis.

33. The typical length for C-C single bond is 154 pm, which is 0.154 nm, therefore it better supports the use of λmax in this analysis....