A liquid is exposed to infrared radiation with a wavelength of 2.68×10−4 cm.

Question

A liquid is exposed to infrared radiation with a wavelength of 2.68×10−4 cm.2.68×10−4 cm. Assume that all the radiation is absorbed and converted to heat. How many photons are required for the liquid to absorb 13.80 J13.80 J of heat?

number of photons?

Answer 1

E = hc/λ

E = energy of a photon

h = Plancks constant = 6.626x10^-34 J.s

c = speed of light = 3x10⁸ m/s

λ = wavelength in m = 2.68 x 10^-4 cm x (1 m/10² cm) = 2.68 x 10^-6 m

E = (6.626x10^-34 Js)(3x10⁸ m/s) / 2.68x10^-6 m

E = 7.42 x10^-20 J

Number of photons required:

13.80 J x 1 photon / 7.42x10^-20 J = 1.86 x 10²⁰ photons ___ Answer!