由2种固体组成的混合物,加热分解后残渣固体的质量是原混合物质

由2种固体组成的混合物,加热分解后残渣固体的质量是原混合物质量的一半,这组混合物可能是(    )

A.Mg(HCO3)2和MgCO3                     B.Na2CO3和NaHCO3

C.CaCO3和MgCO3                           D.SiO2和NaCl

答案

解析:要满足“由两种固体组成的混合物,加热分解后残渣固体的质量是原混合物质量的一半”的题目要求,就必须满足;其中一种固体加热分解后残渣固体的质量小于原固体质量的一半,而另一种固体加热分解后残渣固体的质量大于原固体质量的一半。

    A中,加热分解后的产物均为MgO,两种固体加热分解后残渣固体的质量都小于原固体质量的一半,故不满足题目要求;B中,Na2CO3受热不分解,NaHCO3受热分解成Na2CO3,两种固体加热分解后残渣固体的质量都大于原固体质量的一半,故不满足题目要求;C中,100 g CaCO3受热分解,残留56 g CaO,残留固体的质量大于原固体质量的一半。而84 g MgCO3受热分解,残留40 g MgO,残留固体的质量小于原固体质量的一半。故“C”成立;D中,加热条件下,SiO2和NaCl均不分解,故不满足题意。

答案:C


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