问题 填空题

(10分)高炉炼铁过程中发生的主要反应为:1/3Fe2O3(s)+CO(g)2/3Fe(s)+CO2(g)

温度/℃100011501300
平衡常数4.03.73.5
已知该反应在不同温度下的平衡常数如下:

请回答下列问题:

(1)该反应的平衡常数表达式K=      ,△H      0(填“>”、“<”或“=”);

(2)在一个容积为10L的密闭容器中,1000℃时加入Fe、Fe2O3、CO、CO2各1.0 mol,反应经过l0 min后达到平衡。求该时间范围内反应的平均反应速率υ(CO2)=      、CO的平衡转化率=        

(3)欲提高(2)中CO的平衡转化率,可采取的措施是      

A.减少Fe的量      B.增加Fe2O3的量     C.移出部分CO2

D.提高反应温度    E.减小容器的容积      F.加入合适的催化剂

答案

c(CO2)/ c(CO)(2分)<(2分)

⑵6×103mol/(L·min)(2分)    60%(2分)   ⑶c(2分)

(1)平衡常数是指在一定条件下的可逆反应中,当达到平衡状态时,生成物浓度的幂之积和反应物难得的幂之积的比值,所以其表达式为K=c(CO2)/ c(CO)。根据有关数据可知,温度越高平衡常数越小,所以升高温度,平衡向逆反应方向移动,即正反应是放热反应。

(2)设平衡时CO的物质的量浓度是x,则消耗CO的浓度是0.1-x,生成CO2也是0.1-x,平衡是CO2就是0.1-x+0.1=0.2-x。根据平衡常数可知          ,解得x=0.04mol/L,所以消耗CO是0.1mol/L-0.04mol/L=0.06mol/L,则其转化率是0.06÷0.1×1005=60%。CO2的反应速率是0.06mol/L÷10min=6×103mol/(L·min)。

(3)固体质量的变化,不影响平衡状态,AB不正确。C是解得生成物浓度,平衡向正反应方向移动,转化率增大。正反应放热,升高温度平衡向逆反应方向移动,转化率降低。反应前后体积不变,改变压强,平衡不移动。同样催化剂也不能影响平衡状态,所以正确的答案是C。

不定项选择
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