Question

calculate the energy change resulting from the emission of 1.00 mole of photons at this 470 nm wavelength.

energy per photon = $4.23 \times 10^{-19}$ j/photon

e = ? kj/mole

Explanation:

Step1: Multiply by Avogadro's number

$E = 4.23 \times 10^{-19}\ \text{J/photon} \times 6.022 \times 10^{23}\ \text{photons/mole}$

Step2: Convert J to kJ

$E = \frac{4.23 \times 10^{-19} \times 6.022 \times 10^{23}}{1000}\ \text{kJ/mole}$

Step3: Calculate the final value

$E = \frac{254730.6}{1000}\ \text{kJ/mole}$

Answer:

$255\ \text{kJ/mole}$ (rounded to 3 significant figures)