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质量守恒定律是初中化学中的一个重要定律,它从质量方面阐述了化学变化的规律。本文就其在化学计算中的应用,举例说明。1 应用质量守恒定律求式量(或原子量) 例1 在3X+Y_2=Z的反应中,X的原子量为24,Z的式量为100,Y的原子量为( )。 (A)14 (B)28 (C)32 (D)40 解:设Y的原子量为a。根据质量守恒定律可得3×24+2a=100,则a=14。故选(A)。2 应用质量守恒定律确定物质的元素组成和某些元 素的质量
The law of conservation of mass is an important law in chemistry of junior middle school. It explains the law of chemical change from the aspect of quality. This article gives an example of its use in chemical calculations. 1 Application of conservation of mass law (or atomic weight) Example 1 In the 3X+Y_2=Z reaction, the atomic weight of X is 24, the formula of Z is 100, and the atomic weight of Y is (). (A)14 (B)28 (C)32 (D)40 Solution: Let Y have atomic weight a. According to the law of mass conservation, 3*24+2a=100 can be obtained, then a=14. So choose (A). 2 Application of the law of conservation of mass to determine the elemental composition of a substance and the quality of certain elements