Chapter 13 & 14 CHM 411 Spring 2013 Suroviec

I. UV-Vis molecular absorption

I. Beers Law Deviations and limitations to Beers Law:

Example A solution containing 5.24 mg/100 mL of A (MW 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.

Example A simultaneous determination for cobalt and nickel gives the following information: Calculate the molar concentration of nickel and cobalt. Molar Absorptivity365 nm700 nm Co Ni Absorbance (1.00 cm cell)365 nm700 nm Unknown

II. Types of Instruments 1. Single Beam2. Multichannel

III. Applications A.Absorbing species Absorption of UV-VIS radiation is excitation of bonding electrons Electronic transitions: ,  and nonbonding

B. Types of transitions