一、要准确理解质量守恒定律(1)该定律的适用范围:只适用于化学变化,而不适用于物理变化,如1g冰融化成1g水,虽然这一变化前后的质量相等,但它是物理变化,不能说这一变化符合质量守恒定律。(2)“参加反应”的函义:对于反应物来说,一定要强调是指“参加反应”的物质,不是各反应物质量的简单相加,一定不要把没有参加反应的反应物的质量计算在反应前的物质质量总和中,如有 First, we must accurately understand the law of conservation of mass (1) The law of the scope of application: applies only to chemical changes, not suitable for physical changes, such as 1g ice melt into 1g of water, although this change before and after the same quality, but it is Physical changes, can not say that this change in line with the law of conservation of mass. (2) The meaning of “participation reaction”: for reactants, it must be emphasized that “participate in the reaction,” the material is not a simple sum of the quality of the reactants, must not participate in the reaction The mass of the reactants is calculated as the sum of the masses of the materials before the reaction, if any