This is question about equation E=m*c2. Why this equation does not required any condition of matter? Case 1: I take two mole (4 Kg)H2 & one mole(32 Kg)O2 & make water & get energy. 2H2 (4 Kg Hydrogen)+O2 (32 Kg Oxygen)=2H2O(36 Kg of water)+ 572 KJ Energy Now I convert this water into energy by equation E=m*c2. Total energy I get is QTotal= (36*c2) + 572 KJ Energy. »»» Now instead of I convert hydrogen & oxygen into water, I directly convert both gases into energy so total Energy I getting is, QTotal= m*c2 =(36*c2) Only. This energy is lesser as compared to first one by amount of “572 KJ Energy”. Case 2: I have one Kg of boiled water at 100 degree centigrade. Now I extract 418.7 KJ energy from the water & make it of zero degrees centigrade. Water at 100 C - 418.7 KJ Energy =Water at 0 C. Now I convert this zero degree water into energy, Total energy I getting is, QTotal=1*c2+418.7 KJ energy »»» Now I directly convert boiling water into energy, I getting energy is QTotal=m*c2=1*c2. This energy is lesser as compared to first one by amount of “418.7 KJ Energy”. Why it is occurs? Why energy librated is different for the same initial & final condition of mass?