Final answer:
The energy of a mole of photons with a wavelength of 665 nm is 2.98 × 10^-19 J.
Step-by-step explanation:
The energy of a photon can be calculated using the formula E = hc/λ, where E is the energy, h is Planck's constant (6.626 × 10^-34 J·s), c is the speed of light (3.00 × 10^8 m/s), and λ is the wavelength of the photon. In this case, the wavelength is given as 665 nm. To convert this to meters, divide by 10^9: 665 nm = 665 × 10^-9 m. Plugging in the values into the formula, we get:
E = (6.626 × 10^-34 J·s) × (3.00 × 10^8 m/s) / (665 × 10^-9 m) = 2.98 × 10^-19 J
Therefore, the energy of a mole of photons with a wavelength of 665 nm is 2.98 × 10^-19 J.