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s. A solution containing 5.24 mg/100 mL of A (335 g/mol) has a transmittance of

ID: 1031486 • Letter: S

Question

s. A solution containing 5.24 mg/100 mL of A (335 g/mol) has a transmittance of 55.2% in a 1-50 cm cell at 425 nm. Calculate the molar absorptivity of A at this wavelength. (6 pts) Recall A - -log T 9. Real deviations are considered to be fundamental limitations to Beer's Law Describe a real deviation from Beer's Law as well as its effect of the curve. (4 pts) 10. One electronic transition is "blue-shifted" (hypsochromic) with an increase in solvent polarity. Explain what is meant by "blue-shifted" (4pts). 11. Consider the titration curves below. For credit, you must use inequality symbols to describe the relative molar absorptivities of the sample, product and titrant. (6 pts) 12. A solution containing the complex formed between Bi(III) and thiourea has a molar absorptivity of 9.32 x 10 L em at 470 nm. What is the absorbance of a 6.24 x 103 M solution of the complex at 470 nm in a 1.00 cm cell? (6 pts)

Explanation / Answer

8)

Beer’s law, A = bc

First, we want to determine A from T = 55.2%, A = -log (T) = 0.258,

Then, we want to calculate the molar concentration:

C = (5.24 x 10-3 g/335 g/mol)/(100 mL/1000mL/L)

= 0.00156 M

Using Beer’s law, = A/bc

= 0.258/1.5 cm/0.00156 M

= 110 L/(cm mol)