问题 问答题

(Ⅰ)化学平衡常数K表示可逆反应的进行程度,K值越大,表示______;K值大小与温度的关系是:温度升高,K值______(填“一定增大”、“一定减小”、或“可能增大也可能减小”).

(Ⅱ)在一定体积的密闭容器中,进行如下化学反应:CO2(g)+H2(g)⇌CO(g)+H2O(g)其化学平衡常数K和温度t的关系如下表:

t℃70080083010001200
K0.60.91.01.72.6
回答下列问题:

(1)该反应的化学平衡常数表达式为K=______.

(2)该反应为______反应(填“吸热”或“放热”).

(3)能判断该反应是否达到化学平衡状态的依据是______(多选扣分).

A.容器中压强不变 B.混合气体中c(CO)不变

C.υ(H2)=υ(H2O)D.c(CO2)=c(CO)

(4)某温度下,平衡浓度符合下式:c(CO2)•c(H2)=c(CO)•c(H2O),试判断此时的温度为______℃.

(5)某温度下,将CO和水蒸气各1mol置于密闭容器中反应,达到平衡后测得CO2为0.6mol,再通入4mol水蒸气,达到新的平衡后CO2的物质的量的范围是______.

答案

(Ⅰ)化学平衡常数K表示可逆反应的进行程度,利用生成物平衡浓度你次方乘积除以反应物平衡浓度米吃减肥乘积,K值越大,可能反应进行彻底越大,K值大小与温度的关系是:若反应是放热反应,温度升高,平衡逆向进行,K减小,若反应是吸热反应,升温平衡正向进行,K增大;

故答案为:可逆反应进行的程度越大,可能增大也可能减小;

(Ⅱ):(1)因平衡常数等于生成物的浓度幂之积除以反应物的浓度幂之积,所以K=

c(CO)c(H2O)
c(CO2)c(H2)

故答案为:

c(CO)c(H2O)
c(CO2)c(H2)

(2)化学平衡常数的大小只与温度有关,升高温度,平衡向吸热的方向移动,由表可知:升高温度,化学平衡常数增大,说明化学平衡正向移动,因此正反应方向吸热,

故答案为:吸热;

(3)A、反应是一个反应前后体积不变的反应,压强的改变不会要引起平衡移动,故A错误;

B、化学平衡时,各组分的浓度不随时间的改变而改变,混合气体中c(CO)不变使品红标志,故B正确;

C、化学平衡状态的标志是v=v,所以v(H2)=v(H2O)表明水的正逆反应速率相同,表明反应达到平衡状态,故C正确;

D、c(CO2)=c(CO)时,和起始量与转化率有关,不能表明正逆反应速率相等,达到了平衡状态,故D错误.

故选BC;

(4)平衡浓度符合下式c(CO2)•c(CH2)=c(CO)•c(H2O)时,浓度熵和平衡常数相等均等于1,平衡常数只值受温度的影响,当K=1时,根据表中数据,所以温度是830℃,

故答案为:830;

(5)根据题意:CO+H2O(g)⇌CO2 +H2

初始物质的量:11 0 0

变化物质的量:0.60.60.6 0.6

平衡物质的量:0.40.40.6 0.6

此时二氧化碳和氢气的物质的量之和是1.2mol,再通入4mol水蒸气,化学平衡会向着正反应方向进行,假设一氧化碳全部转化完毕,则会生成二氧化碳和氢气各0.4mol,此时CO2的物质的量1mol,但是一氧化碳不会全部转化,所以达到新的平衡后,CO2的物质的量介于0.6mol-1mol之间;

故答案为:0.6mol>n(CO2)<1mol.

阅读理解

阅读理解。

    

     Sitting on exercise balls brings more than a smile to students and teachers.

     Some fourth-graders at Conrad Weiser West Elementary School in Womelsdorf love their new

chairs--probably because they're not really chairs at all. The kids are sitting on the air-filled balls. But

different from those just for exercise, these have small legs that keep them from rolling. Sitting on a chair

all day in school can make anyone want to move around. So, more and more teachers are letting students

have a ball. By using exercise balls instead of common chairs, teachers find students' posture (姿势) and

attention improved.

     Dotti Pownall, a fifth-grader teacher in West Virginia, has been using balls as chairs since December

2008."The students love them." she says. Pownall took a survey of her students. She found that 80 percent,

thought sitting on the balls helped them concentrate (专注) better: "Besides, they're fun," says Pownall.

     According to WittFitt,  a company that has sold balls to more than 200 schools, they can improve kids'

posture and classroom behavior.

     Exercise ball chairs are getting popular in classrooms, from preschool to college. Some adults (成人)

even use them at work. Lisa Witt felt so strongly about the use of balls as chairs that she started WittFitt.

She said the company not only encourages the use of balls but also educates teachers and students on how

to use them."We sell balls in 24 states in America, three provinces in Canada and Japan." says Witt.

1. Sitting on exercise balls can ______.

A. improve students' attention

B. make students smarter

C. keep students moving around

D. help students become fit

2. According to the passage, the company WittFitt ______.

A. began to produce balls in 2008

B. sells balls in 24 countries

C. was set up by Lisa Witt

D. is famous around the world

3. It can be seen from the passage that ______.

A. exercise balls have no legs

B. Pownall works as a teacher

C. students hate exercise balls

D. exercise balls are filled with sand

4. The passage mainly tells us about ______.

A. the shape of exercise balls

B. the use of exercise balls

C. the number of exercise balls

D. the inventor of exercise balls

单项选择题 A1/A2型题