chem help pleaassse?

Question

3.An atomic gas absorbs red light of wavelength 653 nm


What is the energy difference (kJ) between the two quantum states involved in the absorbtion ?

4.If a certain source emits radiation of wavelength 355. nm what is the energy, in kJ, of one mole of photons of this radiation?

Answer 1

Wavelength 653 nm is corresponding to the frequency of c/λ = (2.998x10^8m/s)/(653x10^-9m) = 4.59x10^14/s.
According to Planck's equation: E = hf, where h the Planck's constant, h = 6.626x10^-34 Js, and f the frequency, we have:
E = (6.626x10^-34 Js)*(4.59x10^14/s) = 3.042x10^-19 J for one photon.
For one mole, E = (3.042x10^-19 J)*6.022x10^23 = 183 kJ
That is the energy difference (kJ) between the two quantum states involved in the absorbtion.

The same calculation: E = (6.022x10^23)*(6.626x10^-34 Js)*(2.998x10^8m/s)/(355x10^-9m) = 337 kJ