Light Relationship

Question

What is the energy of 4.25 x 10^–3 moles of 4.82 nm X-ray photons?  in kj

Answer 1

first you must find the energy in Joules carried by 1 photon of light at 4.82 nm using the equation E=hc/λ

h(planks constant) = 6.626 E-34 JS

c(speed of light)=2.998E8 m/s

λ(wavelength in meters)=4.82E9

E=(6.626E-34)(2.998E8)/(4.82E9)= 4.12E-35 J

this is the amount of energy given off by 1 photon of light

now, there are 6.022E23 photons per mole (avogadro's number)

4.12E-35 J/photon X (6.022E23 photons/mol)= 2.419E-11 joules/mol

we have 4.25E-3 mols X (2.419E-11 J.mol) =1.055E-13 J= 1.055E-16 kJ