问题 填空题

(8分)2010年春,发生在滇、黔、桂、渝、川等省的严重旱情牵动了全国人民的心。水是组成生命体的重要化学物质,有关水的反应有很多。

(1)两个水分子自身作用会生成阴、阳两种离子,其中阳离子的电子式是       

(2)在下列反应中,水仅做氧化剂的是      (填字母,下同),水既不做氧化剂又不做还原剂的是          

A.Cl2+H2O=HCl+HClO

B.2Na2O2+2H2O=4NaOH+O2

C.CaH2+2H2O=Ca(OH)2+2H2

D.3Fe+4H2OFe3O4+4H2(3)“神舟七号”飞船上的能量主要来自于太阳能和燃料电池,H2、O2和KOH的水溶液可形成氢氧燃料电池,负极的电极反应为                    ,电极反应产生的水经冷凝后可作为航天员的饮用水,当得到1.8 L饮用水时,电池内转移的电子数约为       

(4)右图是某品牌饮用矿泉水标签的部分内容。请认真阅读标签内容后计算。

①该矿泉水中镁离子的物质的量浓度的最大值是        

②一瓶合格的这种矿泉水中硫酸根离子的物质的量不能超过         mol。

答案

(1)(2)CD  (3) H2-2e+2OH=2H2O   200NA

(4)①2×104mol/L   ②1×104mol

题目分析:(1)两个水分子自身作用会生成阴、阳两种离子,其中阳离子是H3O,其电子式是

(2)失去电子的物质做还原剂,得到电子的物质做氧化剂,所以A中氯气、B中过氧化钠既是氧化剂也是还原剂,而水既不做氧化剂又不做还原剂。C和D反应中,水中的氢元素化合价降低,做氧化剂。

(3)原电池中负极失去电子,因此氢气在负极通入,负极的电极反应为H2-2e+2OH=2H2O。1.8L水的物质的量是100mol,所以转移电子的物质的量是200mol,则电子式是200NA

(4)①镁离子浓度的最大值是4.8mg/L,而4.8mg镁离子的物质的量是0.0048g÷24g/mol=0.0002mol,所以浓度是2×104mol/L。

②根据SO42的浓度可知,一瓶合格的这种矿泉水中硫酸根离子的质量不能超过19.2mg/L×0.5L=9.6mg,所以物质的量不能超过0.0096g÷96g/mol=1×104mol。

点评:该题属于中等难度的试题,主要考查学生的基础知识和灵活运用知识解决实际问题的能力。只要能熟练掌握常见的化学基础知识,就不难做出。

单项选择题
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A victim of climate change

A polar bear's dead body found on the Arctic island of Svalbard, the northernmost part of Norway, has shocked experts who say climate change may be to blame for the animal’s death.The starved polar bear in Norway was said to be in good health in April when the Norwegian Polar Institute examined and labeled it. However, the animal was reduced to skin and bones by the time a group of explorers came across its body in July.

The bear is thought to have been heading north in a desperate search for sea ice that would allow it to hunt for seals.

"From his lying position in death the bear appears to simply have starved and died where he dropped," polar bear expert Dr. Ian Stirling, a professor at the University of Alberta said, "He had external suggestion of any remaining fat, having been reduced to little more than skin and bone."

Stirling believes the bear starved to death as a result of a lack of sea ice which the animals use as a platform for hunting seals. That may also explain why the 16-year-old male bear was found about 155 miles north of where it was seen in April.

Arctic sea ice reached a record low in 2012, according to a report released this week by the National Oceanic and Atmospheric Administration that pointed to continued signs of climate change.

The International Union for Conservation of Nature currently classifies polar bears as vulnerable on its Red List of Threatened Species.

小题1:How did Stirling know the reason for the death of the polar bear?

A.By the food he ate

B.By doing further experiments

C.By observing other polar bears

D.By his lying position in death小题2:The underlined word "vulnerable" probably means _____

A.easily hurt

B.difficult to hunt

C.dangerous

D.amazing小题3:What is the author's attitude to the incident?

A.Favorable.

B.Uncaring

C.Doubtful.

D.Concerned小题4:Where does this text probably come from?

A.A novel.

B.A guidebook

C.A news report.

D.An advertisement