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 $=h{\nu }_0$
$=6.6\times 10^{-34}kg{m}^2{s}^{-1}\times 2.5\times 10^{14}{s}^{-1}$
$=16.5\times 10^{-20}$ J
Binding energy of 1 mol $e^{-}=16.5\times 10^{-20}\frac{J}{e^{-1}}\times \frac{6.023\times 10^{23}}{1mol}{e}^{-}$
$=99.38\times 10^3$ J/mol
$=99.38$ kJ/mol