问题 实验题

近几年我国某些城市酸雨污染较为严重,主要是因为大量燃烧含硫量高的煤而形成。

【提出问题】通过实验证明煤中含有碳元素和硫元素。

【查阅资料】(1)“二氧化硫能使高锰酸钾溶液褪色(由紫红色变为无色),该反应的化

学方程式为:5SO2 + 2KMnO4 + 2H2O = K2SO4 + 2MnSO4 + 2 X ”。这个化学方程式中

最后一种物质X的化学式是:         

(2)“二氧化硫和二氧化碳一样,也能使澄清石灰水变浑浊。”请写出二氧化硫与澄清石灰水反应的化学方程式:                               。并写出实验室制取二氧化碳的化学方程式:                      

根据上述资料,甲同学、乙同学和丙同学分别设计实验方案进行探究。

【实验探究】(3)甲同学:“实验操作”:甲同学进行了如下图所示A、B两步实验:

“实验现象”: A中稀高锰酸钾溶液褪色,B中澄清石灰水变浑浊。

“得出结论”:煤燃烧生成二氧化硫和二氧化碳,证明煤中含有碳元素和硫元素。

(4)乙同学认为甲同学的实验方案不合理,其理由是:              

(5)丙同学:

“实验操作”:丙同学进行了如下图所示实验(部分装置在图中略去):

【探究与结论】(6)上图C装置的作用是                                   

(7)要证明煤中含有碳元素和硫元素的现象是:丙同学的实验中                                   

答案

(1)H2SO4

(2)①Ca(OH)2+SO2=CaSO3↓+ H2O  ;

②CaCO3+2HCl=CaCl2+H2O+CO2↑ 。

(4)二氧化碳和二氧化硫都能使澄清石灰水变浑浊,不能说明问题 。

(6)除去二氧化硫  ;

(7)B中稀高锰酸钾褪色说明有二氧化硫,证明煤中有硫元素,D中澄清石灰水变浑浊说明有二氧化碳,证明煤中有碳元素 。

题目分析:(1)依据质量守恒定律化学反应前后原子的种类和数目不变:反应前S:5, K:2,Mn:2,O:20,,H:4;反应后S:3, K:2,Mn:2,O:12,,H:0,X前有系数2,故化学式为H2SO4 ;

(2)二氧化硫与澄清石灰水反应的化学方程式:Ca(OH)2+SO2=CaSO3↓+ H2O  ;实验室用碳酸钙和稀盐酸制取二氧化碳:CaCO3+2HCl=CaCl2+H2O+CO2↑;

(4)二氧化碳和二氧化硫都能使澄清石灰水变浑浊,不能说明问题 ;

(5)B装置用于检验二氧化硫的存在,C装置用于除去二氧化硫;D装置用于检验二氧化碳的存在;

(7)B中稀高锰酸钾褪色说明有二氧化硫,证明煤中有硫元素,D中澄清石灰水变浑浊说明有二氧化碳,证明煤中有碳元素 。

单项选择题
阅读理解

An annularity(日环食) is expected to cross China Friday afternoon, a researcher with the Purple Mountain Observatory under the Chinese Academy of Sciences said Wednesday.

The phenomenon, predicted to be the longest annularity of the next 1,000 years, can be seen in some areas of Yunnan, Sichuan, Guizhou, Shaanxi, Hunan,  Hubei,  Henan, Anhui, Jiangsu and Shandong provinces as well as Chongqing.

A partial eclipse(日偏食) would be seen in most of the rest of China, except for the northeast tip of Heilongjiang Province, said Cheng.

According to the National Aeronautics and Space Administration (NASA) of the United States, the annularity will begin in Africa and pass through the Indian Ocean, where the maximum duration(持续的时间) of annularity will reach 11 minutes and 8 seconds.

It will continue into Asia through Bangladesh, India, Myanmar and China. Cheng said the annularity will end at Jiaodong peninsula in Shandong Province, China.

The longest duration of the annularity on China’s territory would be 8 minutes and 17 seconds in Ruili, Yunan Province. A sunset with the annularity would be seen in some areas of Shandong, Guangdong and Taiwan, said Cheng.

An annularity occurs when the moon does not cover the entire disc of the sun so that a ring of light encircles the shadow of the moon.

Another expert said that though an annularity was not considered as wonderful as a total solar eclipse and was of little value in scientific research. It was interesting for the general public to watch the phenomenon, though.

60.The annularity mentioned in the passage is unusual because        .

A. it is expected to cross all over China

B. it begins in Africa and passes through Asia

C. it is of great importance in scientific research

D. it lasts the longest in the next one thousand years

61.From the passage we may conclude that people in Fujian can only enjoy the scene of      .

A. an annularity            B. a partial solar eclipse

C. a total solar eclipse           D. a sunset with the annularity

62.People       can enjoy the longest duration of the annularity on Friday.

A. in Africa    B. in India      C. in China     D. on the Indian Ocean

63.Which of the following is TRUE according to the text?

A. The annularity will end in Shandong Province.

B. The annularity can be seen by people all over China.

C. The phenomenon is an exciting one to the astronomers only.

D. A partial eclipse occurs when a ring of light encircles the shadow of the moon.