Assignment3

Assignment3 - ) (c) Phosphorescence ( 3 pts ) (d)...

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Analytical Methods (CHEM 207) Assignment 3: Tuesday, November 16, 2010 Due: Monday, November 22, 2010 Name: Kelley Krueger ______ 1. Amines react with picric acid to form amine picrates, which absorb strongly at 359 nm (molar absorptivity, ε = 1.25 × 10 4 Mol -1 cm -1 ). An unknown amine picrate ( 0.115 g ) is dissolved in water and diluted to 100.0 mL . A 1-mL aliquot of this solution is further diluted to 250.0 mL for spectrophotometric measurement. If the the absorbance for the final solution is 0.454 at 359 nm using a 1.00-cm cell, what is the formula weight of the amine picrate? ( 3 pts ) 2. With the aid of diagrams, briefly describe the following spectroscopic phenomena for the interaction of molecules with light (a). Light absorption ( 3 pts ) (b) Light emission ( 3 pts
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Unformatted text preview: ) (c) Phosphorescence ( 3 pts ) (d) Fluorescence ( 3 pts ) 3. In formaldehyde, the transition n * (T 1 ) occurs at 397 nm while the transition n * (S 1 ) occurs at 355 nm. (i) What is the difference in energy (kJ/mol) between the S 1 and the T 1 state? ( 3 pts ) (ii) What is the difference in energy in (i) above attributed to? ( 2 pts ) 4. You are provided with the standard reduction potentials below: Fe 2+ (aq) + 2e-Fe(s) E = -0.440 V Al 3+ (aq) + 3e-Al(s) E = -1.677 V (a). Write down both the cathodic and the anodic half-cell reactions for a functional electrochemical cell formed between the two electrodes. ( 2 pts ) Cathode: Anode: Hence write the balanced overall reaction for the cell. ( 3 pts )...
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Assignment3 - ) (c) Phosphorescence ( 3 pts ) (d)...

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