Q.
One mole of magnesium in the vapour state absorbed 1200kJmol1 of energy. If the first and second ionization energies of Mg are 750 and 1450kJmol−1 respectively, the final composition of the mixture is
1550
228
Some Basic Concepts of Chemistry
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Solution:
Number of moles of one g of Mg=241 =0.0417 1g of Mg(g) absorbs =241200=50kJ
Energy required to convert Mg(g) to Mg+(g) =0.0417×750=31.275kJ
Remaining energy =50−31.275 =18.725kJ
Number of moles of Mg2+ formed =145018.725 =0.013
Thus remaining Mg+will be =0.0417−0.013=0.0287
So,%Mg2+=0.04170.0287×100=68.82% %Mg2+=100−68.82=31.18%