Answer: 165.1kJ
Explanation:
The energy of a photon of wavelength 725nm can be written as:
E = hv = hc/λ .....1
since v = c/λ
Where:
λ = wavelength of photon = 725nm = 725 × 10^-9m
h = Planck's constant = 6.626 × 10^-34 Js
c = speed of light = 3.0 × 10^8 m/s
v = frequency
E = energy of the photon
Substituting the values into equation 1, we have:
E = 6.626×3/725 × 10^(-34+8+9) J
E = 0.02742 × 10^-17 J
E = 2.742 × 10^-19 J
Therefore, for one mole of red photons, according to Avogadro's constant:
1 mole = 6.022 × 10^23 photons
So, the total energy of 1 mole of photons is:
E(total) = 2.742 × 10^-19 J × 6.022 × 10^23 photons
E(total) = 16.51 × 10^4 J = 165.1kJ
Therefore, A mole of red photons of wavelength 725 nm has 165.1 kJ of energy.
