问题 填空题

(12分)NiSO4·6H2O是一种绿色易溶于水的晶体,广泛用于化学镀镍、生产电池等,可由电镀废渣(除含镍外,还含有:Cu、Zn、Fe、Cr等杂质)为原料获得。操作步骤如下:

①用稀硫酸溶液溶解废渣,保持pH约1.5,搅拌30min,过滤。

②向滤液中滴入适量的Na2S,除去Cu2+、Zn2+,过滤。

③保持滤液在40℃左右,用6%的H2O2氧化Fe2+,再在95℃加入NaOH调节pH,除去铁和铬。

④在③的滤液中加入足量Na2CO3溶液,搅拌,得NiCO3沉淀。

  ▲ 

  ▲ 

⑦蒸发、冷却结晶并从溶液中分离出晶体。

⑧用少量乙醇洗涤并凉干。

(1)步骤②除可观察到黑色沉淀外,还可嗅到臭鸡蛋气味,用离子方程式说明气体的产生: ▲  

(2)步骤③中,加6%的H2O2时,温度不能过高,其原因是:  ▲ 

(3)除铁方法有两种,一是用H2O2作氧化剂,控制pH值2~4范围内生成氢氧化铁沉淀;另一种方法常用NaClO3作氧化剂,在较小的pH条件下水解,最终生成一种浅黄色的黄铁矾钠[Na2Fe6(SO4)4(OH)12]沉淀除去。下图是温度-pH值与生成的沉淀关系图,图中阴影部分是黄铁矾稳定存在的区域(已知25℃时,Fe(OH)3的Ksp= 2.64×10−39)。下列说法正确的是  ▲ (选填序号)。

a.FeOOH中铁为+2价

b.若在25℃时,用H2O2氧化Fe2+,再在pH=4时除去铁,此时溶液中c(Fe3+)=2.64×10−29

c.用氯酸钠在酸性条件下氧化Fe2+离子方程式为:6Fe2++ClO3+6H+=6Fe3++Cl+3H2O

d.工业生产中温度常保持在85~95℃生成黄铁矾钢,此时水体的pH约为1.2~1.8

(4)确定步骤④中Na2CO3溶液足量,碳酸镍已完全沉淀的简单方法是:  ▲ 

(5)补充上述步骤⑤和⑥(可提供的试剂有6mol/L的H2SO4溶液,蒸馏水、pH试纸)。

答案

(12分)

(1)S2+2H+=H2S↑(2分)

(2)减少过氧化氢的分解(2分)

(3)cd (2分,漏选得1分,错选不给分)

(4)上层清液呈无色(答静置后向上层液中再加入Na2CO3溶液后没有沉淀生成也给分)(2分)

(5)⑤过滤,并用蒸馏水洗涤沉淀2~3次直至流出液用pH试纸检验呈中性(2分)。

⑥向沉淀中加6mol/L的H2SO4溶液,直至恰好完全溶解(2分)

阅读理解

阅读理解。

     Scientists used to explore (探测 ) on the surface of the ocean. Now they are exploring below the surface,

too. They want to know about ocean water and the plant and animal life deep in the ocean.

     In 1934 the scientist William Beebe dived 3,000 feet below the surface in a hollow steel ball. In 1935

August Piccard dived 10,330 feet. In 1960 his son Jean dived to a depth of 35 ,800 feet.

     All these early dives were deep. But the divers could not stay down for very long. They had to come back

up to the surface after a few seconds. Scientists needed to stay down longer to study life below surface.

Gradually they succeeded. Cousteau, a Frenchman, was able to keep down to a depth of 36 feet for one month

and to a depth of 90 feet for a week.

     Now scientists are developing even better equipment. With this new equipment, man can stay below the

surface for days or even weeks. In 1962 Cousteau set up a research station 35 feet below the surface. Then,

in 1964,he set up another station on the ocean floor of the Red Sea. This was the first undersea station to

operate without help from the surface.

     Many countries are now studying undersea living. The former Soviet Union has an undersea laboratory in

the Crimean Sea. The United States has a laboratory 50 feet down on the ocean floor off the Virgin Islands. In

1970 five men lived there for two weeks. Then a team of five women scientists stayed in the laboratory. Next

came other teams of men. All were there to explore the ocean depths and to make plans for the use of its

resources. Scientists hope to find enough mineral, vegetable, and animal wealth there to provide food for the

entire world.

1. In order to _____,scientists are exploring below the surface of the ocean.

A. know about the ocean water deep in the ocean

B. stay down longer to study life of the plant and animal below the surface

C. know about the plant and animal life deep in the ocean

D. both A and C

2. Who made the deepest dive?

A. William Beebe.

B. August Piccard.

C. Jean Piccard.

D. Cousteau.

3. Who set up the first undersea station?

A. A Frenchman.

B. An American.

C. A Russian.

D. The passage made no mention.

4. Which of the following statement is true?

A. The early divers could not stay down for very long.

B. Up to now only five women scientists have stayed in the undersea laboratory.

C. The purpose of setting up the undersea laboratories is to make plans for the use

    of the resources in the ocean.

D. None of the above is true.

5. The author wants to tell us _____. 

A. that scientists try to explore the ocean depths

B. that scientists try to make use of resources in the ocean

C. about the secret of the plant and animal life in the ocean

D. both A and B

单项选择题