问题
选择题
已知： 3/2CO2(g)＋2Fe(s) = Fe2O3(s)＋3/2C(s) △H=－234.1kJ·mol－1
CO2(g) = C(s)＋O2(g) △H=+393.4kJ·mol－1。
则2Fe(s)＋3/2O2(g)=Fe2O3(s)的△H是
A．－824.2kJ·mol－1
B．－627.5kJ·mol－1
C．+861.6kJ·mol－1
D．+159.3kJ·mol－1
答案
答案：A
CO2(g) = C(s)＋O2(g) △H=+393.4kJ·mol－1知C(s)＋O2(g)= CO2(g) △H=－393.4kJ·mol－1则3/2C(s)＋3/2O2(g)="3/2" CO2(g) △H=－393.4kJ·mol－1*3/2=－590.1kJ·mol－1该式与所给一式相加得2Fe(s)＋3/2O2(g)=Fe2O3(s) △H=－824.2kJ·mol－1故选A。