Question

Calculate energy of one mole of photons of radiation whose frequency as 5 $\times$ ${10}^{14}$Hz.

• A. 199.51 kJ ${mol}^{-1}$
• B. 299.31 kJ ${mol}^{-1}$
• C. 399.31 kJ ${mol}^{-1}$
• D. 499.31 kJ ${mol}^{-1}$

Answer 1

The correct option is A

199.51 kJ ${mol}^{-1}$

One thing we have to keep in mind here.

1 mole = 6.022 $\times$ ${10}^{23}$

Now the energy of a single photon $E=h\nu$
=$6.626\times {10}^{-34}Js\times 5\times {10}^{14}{s}^{-1}$

= (3.313 $\times$ ${10}^{-19}J$)

Energy of one mole of photons

= (3.313 $\times$ ${10}^{-19}$ J)(6.022 $\times$ ${10}^{23}$ ${mol}^{-1}$)

= 199.51 kJ ${mol}^{-1}$