根据相对论中的质能关系E=mc2,如果一个物体以辐射形式放出能量,那么它的质量就要减少,由于在化学变化中将伴随着能量的释放和吸收,经典化学中的质量守恒定律和相对论中的质能关系是相矛盾的;质能关系的存在表明在化学变化中质量不是守恒的,实际上是质能的守恒. According to the mass-energy relationship E = mc2 in the theory of relativity, if an object emits energy in the form of radiation, its mass will decrease. Due to the release and absorption of energy in the chemical change, the law of mass conservation in classical chemistry and The relationship between the mass and the energy in relativity is contradictory. The existence of the mass-energy relationship indicates that the mass is not conserved in chemical changes and is actually the conservation of mass energy.