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 (that is, it takes kj of energy to remove mole of electrons from mole of atoms on the surface of metal; ). what is the maximum wavelength of light that can remove an electron from an atom on the surface of lithium metal?

Explanation:

The work function of the lithium = 279.7 KJ/mol  (Source)

It means that  

1 mole of electrons can be removed by applying of 279.7 kJ of energy.

Also,  

1 mole =

So,  

electrons can be removed by applying of 279.7 kJ of energy.

1 electron can be removed by applying of of energy.

Energy required =

Also,  

1 kJ = 1000 J

So,  

Energy required =

Also,

Where,  

h is Plank's constant having value

c is the speed of light having value

So,  

Also,  

1 m = 10⁻⁹ nm

So,  

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g