问题 填空题

(4分)亚硝酸钠(NaNO2)又称工业盐,其外观类似食盐,但有剧毒。近年来,建筑工地多次发生民工误食工业盐而中毒的事件。利用如下反应可鉴别NaNO2和NaCl。

___KMnO4+___NaNO2+___H2SO4=___MnSO4+___K2SO4+___NaNO3+___H2O

(1)配平上述反应的化学方程式;

(2)指出该反应的氧化剂             

(3)当有2mol氧化剂被还原时,则转移的电子是      mol。

答案

(1)配平反应的化学方程式;

2 KMnO4+ 5 NaNO2+ 3 H2SO4=" 2" MnSO4+1 K2SO4+  5 NaNO3+ 3 H2O   2' 

(2)指出该反应的氧化剂 KMnO4;              1'

(3)当有2mol氧化剂被还原时,则转移的电子是  10     mol。 1'

题目分析:在本题中考察学生对于氧化还原反应中对于氧化剂和还原剂的判定以及反应方程式的配平,KMnO4是常用的强氧化剂,NaNO2则作为还原剂;根据配平的情况知道,Mn由+7价降到了+2价,每mol转移的电子为5mol,由于反应中2mol氧化剂被还原,因此转移的电子为10mol。

点评:本题属于常规考题,对氧化还原反应的配平,应当利用电子得失守恒以及元素守恒,转移的电子数要根据价态进行判断。

完形填空
信息归纳 (本部分共5小题,每小题1分,共5分)
Scientists who study the climate (气候) are still arguing about how fast the earth is warming and how much it will warm, but they do agree that the earth is warming and that it will keep warming if we don’t do anything about it.
Scientists agree that the burning of fossil fuels (化石燃料) like oil and coal cause greenhouse gases to escape (释放) into the air and that these gases are causing most of the warming. Another cause is deforestation ( cutting down trees ) . Trees soak up carbon dioxide  (二氧化碳) , one of the greenhouse gases, from the air.
There are already some changes happening because of global warming. Sea level is rising and some animals are already moving to new homes. It’s already too late to stop global warming completely.
If the warming gets worse, as scientists expect, there may be some kinds of plants and animals that become extinct (灭绝的) because they can’t move to new homes. There may be more storms and floods. Sea level may rise so much that people have to move away from the coasts. Some areas may become too dry for farming.
Global warming is a very difficult problem to fix. People are having a hard time agreeing on what to do about it. For example, everyone agrees that wasting energy is a bad thing to do. But some people think that the federal government (联邦政府) should make laws about it, while other people think it should be up to each person or business to decide what to do.
Many states and businesses in the United States are not waiting until the federal government decides what to do. They have already started working on the problem.
根据短文内容,完成下面表格中的信息。每空词数不限。
Global warming
Causes
1. ______                 __  ;
2. _______                _  ; 
Possible results
3. _______                 _  .
Plants and animals become distinct.
4. _____             _   __  .
People move away from coasts.
Some areas become too dry for farming.
What to do
5. _______                _  .
 
选择题