The work function of an element is the energy required to remove an electron from the surface of the solid element. the work function for lithium is 279.7 kj/mol (that is, it takes 279.7 kj of energy to remove one mole of electrons from one mole of li atoms on the surface of li metal). what is the maximum wavelength of light that can remove an electron from an atom on the surface of lithium metal?

Explanation:

The given data is as follows.

            Energy needed for 1 mole = 279.7 kJ =

                                                       = 279700 J

Therefore, energy required for 1 atom will be calculated as follows.

                          =

As relation between energy and wavelength is as follows.

                  E =

where,    h = planck constant =

               c = speed of light =

            = wavelength

Therefore, putting given values into the above formula as follows.

                  E =

      =  

              =  

or,                         = m

                             = 428 nm

Thus, we can conclude that the maximum wavelength of light that can remove an electron from an atom on the surface of lithium metal is 428 nm.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-