74) (a) h = 6.63 x 10-34 J•s c = 3.00 x 108 m/s E = 2.00 x 105 J/mol
E
= 2.00 x 105 J/mol photons * 1 mol photons/(6.02 x
1023 photons) = 3.32 x 10-19 J/photon
(b) E = hc/wlength
wlength = hc/E = 6.63 x 10-34 J•s * 3.00 x 108
m/s/(3.32 x 10-19 J/photon) = 6.00
x 10-7 m
(c) wlength
= 6.00 x 10-7 m * 109 nm/m = 600 nm
This wavelength corresponds to yellow light in the electromagnetic spectrum. Red light has wavelengths about 700 nm and does not transfer enough energy to initiate electron transfer.