CHEMISTRY 31

Quiz 4 - Solutions

Some constants: h = Planck’s Constant = 6.63 x 10^-34 J s; c = speed of light = 3.00 x 10⁸ m/s

1. Some X-ray detectors give a signal proportional to the energy of the light. What is the energy of one photon of an X-ray with a wavelength of 0.72 nm? (6 pts)

E = hc/l = (6.63 x 10^-34 J s)(3.00 x 10⁸ m/s)/[(0.72 nm)(10^-9 m/nm)] = 2.8 x 10^-16 J

2. What is the purpose of a monochromator? (2 pts) Purpose is to select a single wavelength of light_

3. In gas chromatography, what is normally done to decrease the retention factor (k) of an analyte: (2 pts)

a) use a larger diameter column b) use a longer column

c) use a more polar column d) increase the column temperature