Question

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Question 4 (6 marks) Below you can find the Absorption spectra for 3 different dyes. (a) Determined and calculate the molar absorptivity for each of the three dyes (the concentrations are shown on the top left of each spectrum and the structures in p.7). (b) Explain how the differences in de between the red and blue dyes relate to the different colours of the dyes. Identify the chemical features of each molecule that contribute to this difference. (c) Can you conclusively tell the two red dyes apart using this technique? Why? (d) What is an alternative spectroscopic technique that could be used to distinguish between the red dyes?

Answer 1

Prilinnt 2.95 m niven eontentration 9 1 Now D 1 from dimgaom ;man Ihe n m. he O0 6 :AbAobante Valuu AWhan Lam bul -Boes'A \au , FTom A nnent ry.HHon hus; uting hvalu; : 49 2 164 me wn abotiviry Dye 1112AlurA Red At) has molewlon wai'ghi 116.4 mol- m'i Go x 18- 60x10 A1b 2 21 X 10 B sbeutrum man From So A nm and va Iu e Ab4 07h an u E fromLambnt .'^ \aw] 2.25 121 x t0- moiun- E86 x 10 mel bye 1411 ( fonceau 4R) hu moleal weij nt 601.4 on cendrui on (c)

Sos n m Aman Amam(an) Dye :48 Y101 629 1414 1412 504 A11 SoS 6) Dye 141, thi AmAa the DyesA12 14 phen colorh ar diferent Con juatd 9M Latnéhrsmophomt uitA in Dy ust com pmed to, D.4 usfectively Thus The Furthermort du to 41 5 bengene ins) oabso hon maxima 1411(4), th higher winuetungt for Dye 1419 a ppeans ak he two Td. dyu lannot be coneluively told ih vey ose (e) maxima als absinphion ano the Fhe to One red 0 A the considerably, th n be dittingwxhed by Apectromety masA