When light with a wavelength of 400 nm falls on the surface of sodium, electrons with a kinetic energy of 1.05 10% J mol-1 are emitted. (a) What is the minimum energy needed to remove on electron from sodium? (b) What is the maximum wavelength of light that will cause a photoelectrons to be emitted?

When light with a wavelength of 400 nm falls on the surface of sodium,

1.	When light with a wavelength of 400 nm falls on the surface of sodium, electrons with a kinetic energy of 1.05 10% J mol-1 are emitted. (a) What is the minimum energy needed to remove on electron from sodium? (b) What is the maximum wavelength of light that will cause a photoelectrons to be emitted?
Answer» TION of Energy & Wavelength Explanation:From the photoelectric effect, we can calculate the energy of one photon as: E =hv = hc/λPutting the values we get, E = (6.62 x 10-34 Js x 3 x 108 m/s )/ 300 x 10 -9 m = 6.62 x 10-19 JSo, the energy for one mole of photons =6.62 x 10-19 x 6.022x 1023 = 3.99 x 105 JSinc, kinetic energy of electrons = 1.68 x 10 5 JSo, minimum energy required to remove 1 mole of electrons from sodium = (3.99 x 105 )- (1.68 x 105) = 2.31 x 105 JHence, minimum energy required to remove one electron = 2.31 x 105/ 6.022x 1023 =3.84 x 10-19 JNow, wavelength , λ = hc/E = (6.62 x 10-34 Js x 3 x 108 m/s )/ 3.84 x 10-19 J = 5.17 x 10-7 m = 517 nmHence, the RIGHT answer is "Energy = 3.99 X 105 J & Wavelength = 517 nm"