Q.Assume that each atom in a copper wire contributes two free electron,Estimate the number of free electrons in a copper wire having a

 Q.Assume that each atom in a copper wire contributes two free electron,Estimate the number of free electrons  in a copper wire having a mass 6.4g .(Take mass of copper to be 64g/mol)?

Ans. Each atom of copper of wire contributes two free elctons.

Let the number of atoms in the copper wire is x.

Given the mass of copper wire is 6.4g.

No. of moles=given mass/molar mass

No. of moles=6.4/64

             =64/640

    n       =1/10 mol

Because 

no. of moles=no. of atom/Avagadro number

no. of atoms=n* Avagadro number

x=(1/10)  *6.022*10^23

x=6.022*10^22

if one atom of copper wire contributes two free electrons

then 6.022*10^22 atoms contributes=2*6.022*10^22 

no. of free  electrons is=12.044*10^22