Question

The energy of one mole of photons of radiation of wavelength $300$ $nm$ is (Given $h$ = $6.63 × 10^{–34}$Js, $N_A$ = $6.02 × 10^{23}$ $mol^{–1}$, $c = 3 × 10^8$ $ms^{–1}$)

• A. 235 kJ $mol^{–1}$
• B. 325 kJ $mol^{–1}$
• C. 399 kJ $mol^{–1}$
• D. 435 kJ $mol^{–1}$

Answer 1

Answer: (C)

399 kJ $mol^{–1}$

Answer 2

Wavelength of radiation = $300$ $nm$

Photon energy

= $\frac{hc}λ$

= $\frac{6.63 × 10^{-34} × 3 × 10^8}{300 × 10 ^{-19}}$

= $6.63 × 10^{-19}$ $J$

Energy of $1$ mole of photons

= $6.63 × 10^{-19} × 6.02 × 10^{23} × 10^{-3}$

= $399$ $kJ$