In order to comply with the requirement that energy be conserved, Einstein showed in the photoelectric effect that the energy of a photon (h) absorbed by a metal is the sum of the work function (), the minimum energy needed to dislodge an electron from the metal's surface, and the kinetic energy (Ek) of the electron: h = + Ek. When light of wavelength 357.4 nm falls on the surface of potassium metal, the speed (u) of the dislodged electron is 5.8×105 m/s. What is (in kJ/mol) of potassium?

Complete Question

 In order to comply with the requirement that energy be conserved, Einstein showed in the photoelectric effect that the energy of a photon (h) absorbed by a metal is the sum of the work function (), the minimum energy needed to dislodge an electron from the metal's surface, and the kinetic energy (Ek) of the electron: . When light of wavelength 357.4 nm falls on the surface of potassium metal, the speed (u) of the dislodged electron is 5.8×105 m/s. What is work function (in kJ/mol) of potassium?

The work function is  

Explanation:

From the question we are told that

   Where h is the Planck's constant which has  a constant value of  

              Ek  is the kinetic energy which is mathematically represented as

Where m  is the mass of electron with a constant value  

     The wavelength is  

     The speed of the electron is

This photoelectric effect  can be mathematically defined as

f is the frequency of the incident light  which is mathematically represented as  

    is the work function

So  we have  

substituting value

      =>    

For one mole of  one mole the work function is  

Where N is the avogadro's constant with a value  

So

now in KJ

1.solid

2.carbon dioxide

3.helium