Question

When photons with a wavelength of 310 nm strike a magnesium plate, the maximum velocity of the ejected electrons is 3.45  105 m/s. Calculate the binding energy of electrons to the magnesium surface in KJ/mol.

Answer 1

Write the einstein's photoelectric equation as follows: hf = 0+ž meni where, his planck's constant = 6.63x10-24 Js f is frequency = c is velcoity of light = 3.00 x10 m/s 10 m his wavelength = 310 nm " = 310x10 m 1 nm is binding energy = 7.50 x10-19 J mis the mass of the charge carrier = 9.1x10-31 kg mwe is maximum velocity of the charge carrier = 3.45x10 m/s -------------- Substitute the corresponding values in the above equation and caluclate he = 0 + mv.de 0 = has more - 6.63x10** Jsx3.00x10° m/s 19.1x10-31 kg x(3.45x10ʻ m/s)") 310 x10 m 21*1* 3*15.43x10 m/s) ) Q = 6.42x10-19 – 0.54x10-19 J Q = 5.88x10-19 Jx6.02x103 mol Q = 35.4x10* J/mol = 103) = 354 kJ/mol Therefore, the required solti on is 354 kJ/moll