问题
选择题
我国目前广泛应用三氯氢硅氢还原法制备多晶硅。制备三氯氢硅的反应为：
Si(s)＋3HCl(g) ="=" SiHCl3(g)＋H2(g) ΔH="-210" kJ/mol。
伴随的副反应有：Si(s)＋4HCl(g) ="=" SiCl4(g)＋2H2(g) ΔH="-241" kJ/mol。
SiCl4在一定条件下与H2反应可转化为SiHCl3，反应的热化学方程式为：
A．SiCl4＋H2 ="=" SiHCl3＋HClΔH=" +31" kJ/mol
B．SiCl4＋H2 ="=" SiHCl3＋2HCl ΔH=" -31" kJ/mol
C．SiCl4(g)＋H2(g) ="=" SiHCl3(g)＋HCl(g) ΔH="+31" kJ/mol
D．SiCl4(g)＋H2(g) ="=" SiHCl3(g)＋2HCl(g) ΔH=" -31" kJ/mol
答案
答案：C
正确答案：C
Si(s)＋3HCl(g) ="=" SiHCl3(g)＋H2(g) ΔH="-210" kJ/mol①
Si(s)＋4HCl(g) ="=" SiCl4(g)＋2H2(g) ΔH="-241" kJ/mol②
①-②得SiCl4(g)＋H2(g) ="=" SiHCl3(g)＋HCl(g) ΔH="+31" kJ/mol，C正确。