(a) From the extinction coefficient of isoprene (10,750 M^–1 cm^–1) and its observed absorbance at 222.5 nm (Fig. 15.5), calculate the concentration of isoprene in mol L^–1 (assume a 1 cm light path).

(b) From the results of part (a) and Fig. 15.5, calculate the extinction coefficient of isoprene at 235 nm.

Transcribed Image Text:

FIGURE 15.5 Ultraviolet- visible spectrum of isoprene in methanol. The Amax (red) is the wavelength at which the absorption maximum occurs; for isoprene, the Amax is 222.5 nm. absorbance 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 200 max = 222.5 nm 220 240 H₂C 260 CH3 C H isoprene CH₂ 300 280 wavelength (1), nm 320 340 360