2 gm of hydrogen atom are excited to radiation.the study of spectra indicated 25%of atoms are in third energy level and 20% atoms in second energy level and rest in ground state.calculate the total energy evolved when atoms return to ground state.

Asked by nishac | 22nd Sep, 2010, 09:11: PM

Expert Answer:

1gm of H atom =N atoms
 
2 gm will contain 2*N=2*6.02*1023 =12.04*1023
 
Number of atom in the III rd shell= 12.04*1023 *25/100=3.01*1023
 
Number of atom in the II nd shell= 12.04*1023 *20/100=2.408*1023
 
when all the atoms returns to excited state then,
 
E'=(E3-E1)*3.01*1023
 
=( -13.6/9-(-13.6/1))*1.6*10-19 * 3.01*1023 =6*10joules(approx)
 
E''=(E2-E1)*2.408*1023
 
( -13.6/4-(-13.6/1))*1.6*10-19 * 2.41*1023 =3*10joules(approx)
 
E=E'+E''
 
=6*105 + 3*105 =900 kj(approx)



Answered by  | 23rd Sep, 2010, 08:36: AM

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