A new prototype UV light source emits photons at a wavelength of 366.3 nm

1) Calculate the energy per photon.

2) Calculate the total energy associated with the emission of 1.50 x 10^-1 moles of photons at this wavelength

Question

A new prototype UV light source emits photons at a wavelength of 366.3 nm

1) Calculate the energy per photon.

2) Calculate the total energy associated with the emission of 1.50 x 10^-1 moles of photons at this wavelength

| General Chemistry 2

Accepted Answer

1)

E = $\frac{hc}{λ}$

h = Planck’s constant = 6.626 x 10^-34 m².kg.s^-1

c = speed of light = 2.998 x 10⁸ m.s^-1

λ = wavelength (in m) à 366.3 nm = 3.663 x 10^-7 m

E = $\frac{6.626 \times 10^{- 34} \times 2.998 \times 10^{8}}{3.663 \times 10^{- 7}}$

E = 5.423 x 10^-19 J

2)

E_{n moles photons} = n x N_A x E_{1 photon}

n = number of moles (in mol)

N_A = Avogadro’s number = 6.022 x 10²³

E_{n moles photons} = n x N_A x E_{1 photon}

E_{n moles photons} = 1.50 x 10^-1 x 6.022 x 10²³ x 5.423 x 10^-19 J

E_{n moles photons} = 4.899 x 10⁴ J

Final - Question 9 | General Chemistry 2