搜题请搜索小程序“爱下问搜题”
问题 选择题

一定温度下，2SO2（g）+O2（g）⇌2SO3（g）；△H=-197kJ/mol，将3molSO2和1molO2充入一定容密闭容器中，在催化剂存在下进行下列反应，当达到平衡状态时，下列说法中正确的是（　　）

A．生成SO3为2mol

B．SO3和SO2物质的量之和一定为3mol

C．放出197kJ的热量

D．SO2的物质的量和SO3物质的量一定相等

答案

A、该反应为可逆反应，1mol氧气完全反应才能生成2mol二氧化硫，由于可逆反应不可能完全转化成生成物，所以生成的三氧化硫的物质的量小于2mol，故A错误；

B、根据质量守恒，含有硫原子的物质只有二氧化硫和三氧化硫，反应前有3mol二氧化硫，所以SO3和SO2 物质的量之和一定为3mol，故B正确；

C、热化学方程式中：2SO2（g）+O2（g）⇌2SO3（g）；△H=-197kJ/mol，反应消耗1mol氧气能够放出197kJ热量，由于可能反应中反应物转化率不可能是100%，所以反应中放出的热量小于197kJ，故C错误；

D、达到平衡状态，满足正逆反应速率相等，各组分的浓度不变，而SO2的物质的量和SO3物质的量不一定相等，故D错误；

故选B．

阅读理解

Dear Mr. Wise,
I’m a slow student. Most of my classmates are much better than me, so I usually get stressed out. Although I spend much time studying for the tests, I can’t get good grades. Sometimes my father gives me some help. He tells me not to worry about it, but it doesn’t work. What do you think I should do?
Li Lei
  
Dear Li Lei,
Many famous people were not so good when they were young. Edison, a famous scientist, did poorly in his studies when he was a young boy. But, as an adult, he made many inventions that helped a lot of people. When I was at young age, I didn’t do well at school. I just kept working hard, and at last, I succeed. You should take it easy and try your best. Tomorrow is another day. I believe you can do better.
Mr. Wise
小题1:Li Lei feels worried because ______________.
A．he doesn’t like going to school
B．he is not as good as most of his classmates
C．his father doesn’t like him
D．he doesn’t want to work hard
小题2:Li Lei writes this letter to ______________.
A．ask for some help
B．find a pen pal
C．tell his father his problem
D．let all his classmates know it
小题3:In Mr. Wise’s letter, “Tomorrow is another day” means “____________”.
A．Tomorrow is the weekend
B．One can get good friends tomorrow
C．Tomorrow is the same as today
D．There are a lot of hopes in our lives
查看答案
多项选择题

下列关于水管型压力、压差传感器安装说法正确的是（）。

A、其安装应与工艺管道预制和安装同时进行

B、应安装在便于维修、调试的地方

C、应安装在温、湿传感器的上游侧

D、可以安装在管道焊接缝处

E、应安装在温、湿传感器的下游侧
查看答案