Question

Determine the energy of 1.60 mol of photons for each of the following kinds of light. (Assume three significant figures.)

infrared radiation (1580 nm )

visible light (515 nm )

ultraviolet radiation (165 nm )

Answer 1

n = 1.6 mol

E = hc/WL

for 1.6 mol:

E= h*c/WL * (Na *1.6)

change all WL to meters

then

H = planck constant = 6.636*10^-34

c = speed of light = 3*10^8

then

a)

IR

E= h*c/WL * (Na *1.6)

E=(6.636*10^-34)(3*10^8)/(1580*10^-9)* (6.022*10^23)*(1.6) = 121403.52 J/mol --> 1.21*10^5 kJ/mol

b)

Visible Light

E= h*c/WL * (Na *1.6)

E=(6.636*10^-34)(3*10^8)/(515*10^-9)* (6.022*10^23)*(1.6) = 372461.28466J/mol --> 3.72*10^5 kJ/mol

c)

UV light

E= h*c/WL * (Na *1.6)

E=(6.636*10^-34)(3*10^8)/(165*10^-9)* (6.022*10^23)*(1.6) = 1162530.67636 J /mol --> 1.16*10^6 kJ/mol