在一些有关化学方程式的计算题中,如能分析题目中有关物质量的差值,找准差量与已知量、未知量的关系,然后列比例求解,常会收到事半功倍的效果。例1实验室用H2还原mg氧化铜,加热一段时间,停止加热,冷却称得残留固体为ng,实验过程中共用去wg氢气,则参加反应的氧化铜质量分数__。 In some calculation problems related to chemical equations, if you can analyze the differences in the quality of the items in question, find the relationship between the difference and the known quantity, the unknown quantity, and then solve the column ratio, you will often receive a multiplier effect. Example 1 The laboratory used H2 to reduce mg of copper oxide, heating for a period of time, stopping heating, cooling to obtain the residual solids as ng, sharing wg of hydrogen in the experiment, then participating in the reaction of copper oxide mass fraction __.