Question

2) Frequencies of FM radio stations are usually given in megahertz (MHz), where 1 MHz equals 100 sec !. For a radio station that broadcasts at 94.3 MHz, calculate the following: a) The frequency in sec b) The wavelength of the radiation, in meters c) The wavelength of the radiation, in nanometers d) The photon energy, in joules e) The photon energy, in kJ/mol 3) Molecular bromine (Br) breaks apart into bromine atoms if it is exposed to light whose energy is 190 kJ/mol. a) Calculate the wavelength of this light, in nanometers. b) Does this light fall in the visible spectrum? If not, does it fall in the infrared region, or in the ultraviolet region?

Answer 1

Answer 2 Given Data'r Frequency, i = 94.3 MHz - 94.3 * 100 Hz (a) Frequency, V = 94.3 × 10 Hz To = 94.3 x 10 sectol (= 1 H2 = 1 sec ) (b) Wavelength, a = c at - speed of light & frequency of radia 1 - 3X10% => = 3.18 m) 94.3 X 106 (c) Wavelength d= 3.18 m => A = 3-18 x 10° nm ( lnm = loºm) (d) photon energy, E = he plack's constant E = 6.626 X 10-34 x 3 x 108 3.18 E = 6.25 × 10 26 Joules (e) photon energy, E = 6.25 x 10-26 J E = 6.25 x 10-26 x 6.022 x 1023 small & = 37.6375 x 10 3 J mati E = 3.76 x 10% ws/mell (: 15 = lot)

w Answer 3 Given Data & Energy of light, E = 190 KJ/mol. (a) Wavelength of tength light, a = ? & Energy (soules) Energy of light, & - hc h planck's constant - speed of light 190 x 103 = 6.626 X 10 34 x 3x108 NA & d = 0.104 x 10-29 x 6.022 x 1023 m. d-..-04 x 10-30 X 6.022 x 1023 m d = 6.2628 x 107m 1 = 626.28 x 10.9 m A = 626-28 nm This light fall in the visible spectrum [400 nm to 700 nm