Q1(m). Energy of one einstein

Answer in brief

One einstein is one mole of photons; at 350 nm its energy is 3.418×10⁵ J (341.8 kJ).

Key points

• A photon has energy hc/λ. Thus the energy of one mole of monochromatic photons is E=N_Ahc/λ.
• Insert N_A=6.022×10²³ mol⁻¹, h=6.626×10⁻³⁴ J s, c=2.998×10⁸ m s⁻¹ and λ=350×10⁻⁹ m.
• This gives E=341787 J for one mole of photons.