晶胞是晶体中最小的重复单位，数目巨大的晶胞无隙并置构成晶体．_爱下问搜题

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问题问答题

晶胞是晶体中最小的重复单位，数目巨大的晶胞无隙并置构成晶体．NaCl晶体是一个正六面体（如图一）．我们把阴、阳离子看成不等径的圆球，并彼此相切（已知a为常数）．

请计算下列问题：

（1）每个晶胞平均分摊______个Na⁺，______个Cl^-．

（2）NaCl晶体中阴阳离子的最短距离为______（用a表示）．

（3）NaCl晶体为“巨分子”，在高温下（≥1413℃时）晶体转变成气态团簇分子．现有1molNaCl晶体，加强热使其气化，测得气体体积为11.2L（已折算为标准状况）．则此时氯化钠气体的分子式为______．

答案

（1）该晶胞中钠离子个数=12×

1

4

+1=4，氯离子个数=8×

1

8

+6×

1

2

=4；

故答案为：4，4；

（2）根据图片二知，NaCl晶体中阴阳离子的最短距离为a的一半即

a

2

；

故答案为：

a

2

；

（3）1mol氯化钠的质量=1mol×58.8g/mol=58.5g，标况下，气体体积为11.2L的氯化钠的物质的量=

11.2L

22.4L/mol

=0.5mol，M=

58.5g

0.5mol

=117g/mol，所以氯化钠气体的分子式为Na₂Cl₂；

故答案为：Na₂Cl₂．

判断题

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完形填空

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