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硝酸与金属反应是硝酸的重要化学性质之一，请阅读下文并解答有关问题．

（1）ag铜与bmL浓HNO3充分反应后得到V1L红棕色气体X，且溶液中余下cg铜；再将此红棕色气体通过水变成V2L无色气体Y（气体已转换成标准状况下的体积，设题中产生的氮的化合物分子中均含有一个氮原子．）

①当反应生成X气体时有多少克氮元素被还原？

②计算X气体中各组分的物质的量．

（2）若在（1）反应余下的溶液中加入过量的稀H2SO4使留下的cg铜恰好完全溶解；此时溶液中只留下一种盐．

①写出此时发生的化学反应方程式

②计算a与c的质量比及浓HNO3的物质的量浓度．

答案

（1）铜与浓硝酸反应的方程式为：发生的反应有：Cu+4HNO3（浓）=Cu（NO3）2+2NO2↑+2H2O，随着反应的进行，硝酸浓度降低，则发生：3Cu+8HNO3（稀）=3Cu（NO3）2+2NO↑+4H2O，则红棕色气体为NO2和NO的混合物，

①根据N元素守恒，被还原的硝酸即为生成NO2和NO的物质的量，n（NO2）+n（NO）=

V1
22.4
mol，

m（N）=

V1
22.4
mol×14g/mol=
7V1
11.2
g，

答：当反应生成X气体时有

7V1
11.2
g氮元素被还原；

②再将此红棕色气体通过水变成V2L无色气体Y，发生反应为：3NO2+H2O=2HNO3+NO，

设混合气体中含有xLNO，yLNO2，

则：

x+y=V1
1
3
y+x=V2
，

解之得：x=

3V2-V1
2
，y=
3V1-3V2
2

所以：n（NO）=

3V2-V1
44.8
mol，n（NO2）=
3V1-3V2
44.8
mol，

答：X气体中各组分的物质的量分别为：n（NO）=

3V2-V1
44.8
mol，n（NO2）=
3V1-3V2
44.8
mol；

（2）①反应后溶液中含有NO3-，NO3-在酸性条件下具有强氧化性，能继续与Cu反应，最终产物为CuSO4，反应的方程式为3Cu+Cu（NO3）2+4H2SO4═4CuSO4+2NO↑+4H2O，

答：发生的化学反应方程式为3Cu+Cu（NO3）2+4H2SO4═4CuSO4+2NO↑+4H2O；

②反应的方程式为3Cu+Cu（NO3）2+4H2SO4═4CuSO4+2NO↑+4H2O，

由方程式可知：加入硫酸前与加入硫酸后的Cu的物质的量之比为1：3，

则总的Cu的物质的量与加入硫酸后的Cu的物质的量之比为（1+3）：3=4：3，

质量比为：4：3，

n（Cu（NO3）2）=2×

ag
64g/mol
×
1
4
=
a
128
mol

根据N元素守恒计算总n（HNO3），

n总=n（NO2）+n（NO）+2n（Cu（NO3）2）=

V1
22.4
mol+2×
ag
64g/mol
×
1
4
=（
V1
22.4
+
a
128
）mol

所以：浓HNO3的物质的量浓度为：c=

n
V
=
1000(
a
128
+
V1
22.4
)
b
mol/L，

答：a与c的质量比及浓HNO3的物质的量浓度分别为：4：3； 

1000(
a
128
+
V1
22.4
)
b
mol/L．

阅读理解

任务型阅读。

     Without changes, our lives would be very boring. It would be like listening to the same song on

your MP4 player over and over again.

     Some people don't like changes. They want to do the same things and see the same people every

day. ①当事情变化时,这让他们感觉不舒服. It's like some children. If all their toys aren't in their

places, they can't go to sleep. However, changing is a big part of life and we all change in small ways

every day. The young get stronger and the old get weaker. We meet new friends or we get new

hobbies.

     You'll go through many changes in your life. In America, some people change jobs over ten times

during their lives. Some change their homes many times. They like changing because they think it

improves their lives.

     ②China has seen many changes in recent years and most of them are very good. People are

healthier and they're living longer. People have more money and more food, and they also get a

better education. Children are growing taller and the children in Shanghai are now the tallest in China.

Changes have been good for China and they'll be good for you.

根据短文内容，完成下列任务。

1.任务一：将文中划线的句子①翻译成英语。

________________________________________________

2. 任务二：将文中划线的句子②翻译成汉语。

________________________________________________

3. 任务三：根据短文内容，选择正确答案_____.

Which is TRUE according to (根据) the passage?

A. People are less healthy and they’re living a shorter life in China.

B. The children in Shanghai are now the tallest in the world.

C. Many good changes have taken place in recent years in China.

D. People have less money, but they have a better education in China.

4. 任务四：回答问题。

Why do Americans like changes?

_________________________________________________________________

5. 任务五：给短文拟一个恰当的题目。

_________________________________________________________________
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单项选择题

（）是管理的核心要素，也是管理中最有活力，最积极的要素。

A.财

B.物

C.教师

D.人
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