Calculate The Longest Wavelength Visible To The Human Eye

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. The change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. The minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kJ/mol. Calculate the longest wavelength visible to the human eye.

Answer: 720 nm.

Explanation

Given that 164 kJ/mol is the minimum energy required to change the conformation of 11-cis-retinal in the human eye.

Determine the longest observable wavelength to the human eye. Convert the minimum energy into the energy of individual photons.