Calculate the energy per mole of photons of red light with a wavelength 750 nm. [h = 6.626 × 10^ -34 Js, C = 3 × 10^8 m/s.]

Question

Quantrex Academy · Accepted Answer

Correct answer: A. 1.596 × 10^5 J

The energy of a single photon is given by

E = \dfrac{hc}{\lambda}

.

The energy of one mole of photons is

E_{mole} = N_A \dfrac{hc}{\lambda}

, where

N_A

is Avogadro's number (

6.022 \times 10^{23}

mol

^{-1}

).

Given:

\lambda = 750 \text{ nm} = 750 \times 10^{-9}

m

h = 6.626 \times 10^{-34}

J s

c = 3 \times 10^8

m/s

Substituting the values into the formula:

E_{mole} = \dfrac{6.022 \times 10^{23} \times 6.626 \times 10^{-34} \times 3 \times 10^8}{750 \times 10^{-9}}

E_{mole} = \dfrac{119.7 \times 10^{-3}}{750 \times 10^{-9}}

E_{mole} = 0.1596 \times 10^6 \text{ J mol}^{-1}

E_{mole} = 1.596 \times 10^5 \text{ J mol}^{-1}

Answer:

1.596 \times 10^5

J.

Calculate the energy per mole of photons of red light with a...