Question

The energy of one mole of protons of radiation whose frequency is $ 5 \times 10^{14}\, Hz $ is

• A. $ 192.51\,kJ\, mol^{-1} $
• B. $ 199.51\,kJ\, mol^{-1} $
• C. $ 195.45\,kJ\, mol^{-1} $
• D. $ 170.00\,kJ\, mol^{-1} $

Answer 1

Answer: (B)

Energy of one photon is
$E = hv$
$= 6.626 \times 10^{-34}\, Js \times 5 \times 10^{14} \, Hz$
$ = 3.313 \times 10^{-19} \,J$
$\because$ One mole photons contains
$= 6.022 \times 10^{23}$ photons.
For $1$ mole of photons, total energy
$= 6.022 \times 10^{23} \times 3.313 \times 10^{-19}\,J/mol$
$= 19.9508 \times 10^4\,J \,mol^{-1}$
$= 199.508 \times 10^3\,J\, mol^{-1}$
$= 199.508 \,kJ\, mol^{-1}$