Question

What is the binding energy (in J/mol or kJ/mol) of an electron in a metal, whose threshold frequency for photon electron is $2.5\times 10^{14}s^{- 1}$ ?

• A. 99.38 kJ/mol
• B. $1.66\times 10^{- 19}$ J/mol
• C. $2.75\times 10^{- 43}$ J/mol
• D. $7.22\times 10^{17}$ kJ/mol

Answer 1

Answer: (A)

Binding energy of electron $=h\nu_{0}$
$=6.6\times 10^{- 34}kgm^{2}s^{- 1}\times 2.5\times 10^{14}s^{- 1}$
$=16.5\times 10^{- 20}$ J
Binding energy of 1 mol $e^{-}=16.5\times 10^{- 20}\frac{J}{e^{- 1}}\times \frac{6.023 \times 1 0^{23}}{1 m o l}e^{-}$
$=99.38\times 10^{3}$ J/mol
$=99.38$ kJ/mol