一、设一求一法对于没有给出任何数据的计算题,如果用单纯的数学计算来做,不仅无法入手, 而且易出错,不妨试一下设一求一法．例1 有一包铜和碳组成的固体混合物置于一敞口容器中,在一定条件下与氧气完全反应,生成同体氧化铜和气体二氧化碳,并测得反应前后固体的质量不变,则原固体混合物中碳的质量分数是多少? First, set a one-for-one method For calculation problems that do not give any data, if you use simple mathematical calculations to do it, not only can not start, and error-prone, may wish to try to set a one-shot method. Example 1 A solid mixture of copper and carbon is placed in an open container and reacts completely with oxygen under certain conditions to produce homogenous copper oxide and gaseous carbon dioxide, and the mass of the solid before and after the reaction is measured to be constant. What is the mass fraction of carbon in the mixture?