题目

把1 g含脉石（SiO2)的黄铁矿样品在氧气流中灼烧，反应完全后得0.78 g残渣，则此黄铁矿的纯度是A.33%               B.66%               C.78%                   D.88% 答案：B 解析：本题采用差量法计算。设1 g样品中含FeS2的质量为x。4FeS2+11O22Fe2O3+8SO2    Δm4×120                      2×160          480-320=160 gx                                                     1-0.78=0.22 g    x=0.66 g黄铁矿的纯度为0.66/1×100%=66%。（改错）I want a few water.