# Calculate the Energy of Light in kJ/mol

## If light has a wavelength of 805 nm, what is the energy of this light with units kJ/mol?

How does the frequency of the radiation affect the energy received or released?

## Answer:

The energy of light with a wavelength of 805 nm is 2.469 × 10⁻²² kJ/mol.

When light has a wavelength of 805 nm, the energy of this light can be calculated using the expression:

**E = hc/λ**

Where:

**E** is the energy,

**h** is Planck's constant,

**c** is the speed of light, and

**λ** is the wavelength.

By substituting the values:

**E = 6.626 × 10⁻³⁴ × 2.998 × 10⁸ / 805 × 10⁻⁹**

**E = 2.469 × 10⁻¹⁹ J**

Converting the energy to kJ/mol, we get:

**E = 2.469 × 10⁻²² kJ/mol**

The frequency of the radiation directly affects how much energy is received or released. Only discrete amounts of energy can be discretely emitted or absorbed by various atoms and molecules. Quantum energy is the smallest amount of electromagnetic radiation that can be either emitted or absorbed.