Question

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%

Answer 1

解析：设矿石中FeS₂的质量为x，则

4FeS₂+11O₂====2Fe₂O₃+8SO₂    m

4×120 g                                           160 g

x                                           1 g－0.78 g=0.22 g

x=0.66 g

所以w（FeS₂）==66%。

答案：B