Explain how the value of ΔH for a reaction changes upon each operation:
a. multiplying the reaction by a factor.
b. reversing the reaction.
Why do these relationships hold?
Solution: According to Planck’s quantum theory of radiation, the amount of energy associated with a quantum(in case of light, the quantum of energy is often called photon) of radiation is proportional to the frequency of light, E = h ---(1), where h is a universal constant called Planck’s constant. is the frequency and E is the energy of a photon. Or, E = hc/ -------(2), where, is the wavelength of light and c is the velocity. Step1: a) Given, frequency of the light = 2.94 x 10 s 14 -1 Planck's constant, h = 6.626 x 10 -34J.s Substituting the values in equation (1), we get, E = (6.626 x 10 -34J.s) x (2.94 x 10 s )4 -1 = 19.48 x 10 -20J -19 = 1.948 x 10 J. -19 Thus, energy of one photon of the radiation is 1.948 x 10 J. Step2:...