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问题 填空题

工业上利用软锰矿（主要成分为MnO2，同时含少量铁、铝等的化合物）制备硫酸锰的常见流程如下：

部分金属阳离子以氢氧化物形式完全沉淀时溶液的pH见下表：

沉淀物Al(OH)3Fe(OH)3Fe(OH)2Mn(OH)2
pH5.23.29.710.4
 

（1）一氧化锰用硫酸酸浸时发生的主要反应的离子方程式为____________________。酸浸后加入MnO2将溶液中的Fe2＋氧化成Fe3＋，其目的是___________。

（2）滤渣A的成分除MnO2外，还有_______________。

（3）MnO2是制造碱性锌锰电池的基本原料，放电时负极的电极反应式为________。工业上以石墨为电极电解酸化的MnSO4溶液生产MnO2，阳极的电极反应式为_________，当阴极产生4.48L（标况）气体时，MnO2的理论产量为______g。

（4）锰的三种难溶化合物的溶度积：Ksp(MnCO3)＝1.8×10－11，Ksp[Mn(OH)2]＝1.9×10－13，Ksp(MnS)＝2.0×10－13，则上述三种难溶物的饱和溶液中，Mn2＋浓度由大到小的顺序是_______＞_______＞_______（填写化学式）。

答案

（1）MnO＋2H＋＝Mn2＋＋H2O（2分） 确保铁元素在后续操作中完全转化为氢氧化物沉淀而除去（2分） （2）Al(OH)3、Fe(OH)3（2分）

（3）Zn＋2OH－－2e－＝Zn(OH)2（2分） Mn2＋＋2H2O－2e－＝MnO2＋4H＋（3分）   17.4（3分）

（4）Mn(OH)2＞MnCO3＞MnS（3分）

题目分析：（1）一氧化锰用硫酸酸浸时生成硫酸锰和水，因此发生反应的离子方程式为MnO＋2H＋＝Mn2＋＋H2O；根据表中数据可知，氢氧化亚铁完全沉淀时的pH值是9.7，因此在pH等于5.4的条件下不能沉淀无法除去。而氢氧化铁完全沉淀时的pH值只有3.2，所以酸浸后加入MnO2将溶液中的Fe2＋氧化成Fe3＋的目的是保铁元素在后续操作中完全转化为氢氧化物沉淀而除去。

（2）根据表中数据可知，在pH等于5.4的条件下铝离子与铁离子已经完全转化为氢氧化物沉淀，因此滤渣A的成分除MnO2外，还有Al(OH)3、Fe(OH)3。

（3）MnO2是制造碱性锌锰电池的基本原料，而原电池中负极失去电子，发生氧化反应，该原电池中锌是负极，则放电时负极的电极反应式为Zn＋2OH－－2e－＝Zn(OH)2；电解池中阳极失去电子，发生氧化反应，则工业上以石墨为电极电解酸化的MnSO4溶液生产MnO2，则锰离子在阳极放电，因此阳极的电极反应式为Mn2＋＋2H2O－2e－＝MnO2＋4H＋；电解池中阴极得到电子，发生还原反应，则阴极是溶液中的氢离子放电产生氢气。当阴极产生4.48L（标况）氢气，其物质的量是0.2mol，转移0.2mol×2＝0.4mol电子，所以根据电子守恒可知，阳极生成二氧化锰的物质的量是0.2mol，则MnO2的理论产量为0.2mol×87g/mol＝17.4g。

（4）锰的三种难溶化合物的溶度积：Ksp(MnCO3)＝1.8×10－11，Ksp[Mn(OH)2]＝1.9×10－13，Ksp(MnS)＝2.0×10－13，由于碳酸锰与硫化锰的组成特点相似，因此溶液中的锰离子浓度与溶度积常数成正比，即溶度积常数越大，锰离子浓度越大，所以Mn2＋浓度是MnCO3＞MnS。根据溶度积常数可知，碳酸锰和氢氧化锰溶液中Mn2＋浓度分别为、，显然前者大于后者，所以上述三种难溶物的饱和溶液中，Mn2＋浓度由大到小的顺序是Mn(OH)2＞MnCO3＞MnS。

选择题

—May I ask you some questions, Dr. Wang?

—_______[ ]

A. You're welcome.

B. Sure, go ahead.

C. No, I'm busy.

D. Yes, you must.
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单项选择题

It was two years ago today that the hunting ban came into force, supposedly ending centuries of tradition. However, the law has been an unmitigated failure—not that either side is shouting about it.
It was a nightmare vision that struck fear and loathing into the hearts of millions. When the hunting ban became law, it was said, 16,000 people would lose their jobs, thousands of hounds would be put down, rotting carcasses would litter the countryside, hedgerows would disappear, riders would face on-the-spot fines, law-abiding people from doctors to barristers would be dragged from their horses and carted off to prison, while dog owners would be prosecuted if their mutt caught a rabbit.
These were just some of the claims as desperate countryside campaigners battled to save their sport in the lead—up to the hunting ban, which Labour rammed into law using the Parliament Act on November 18, 2004.
For many, the fears were real. Others exaggerated as they fought an increasingly aggressive anti-hunting lobby which had rejected acres of independent evidence affirming that hunting is the most humane way of killing foxes. In the battle to "fight prejudice, fight the ban", every emotive argument was deployed.
For its part, the anti-hunting brigade extravagantly claimed that the ban would put an end to the rich parading in red jackets. A senior Labour MP, Peter Bradley, admitted in this newspaper that it was, as many suspected, about "class war". He lost his seat shortly afterwards. But people in red coats did not disappear.
In fact, none of the forecasts came true. What did happen was something nobody had predicted: the spectacular revival and growth of hunting with hounds. In short, the hunting ban has been a failure.
Today, on the second anniversary of the ban’s coming into force on February 18, 2005, new figures show that participation in the sport has never been higher. It is so cheerful that two new packs have been formed, something that has not happened for centuries.
They include the seductively named Private Pack, set up by the financier Roddy Fleming in Gloucestershire. It operates on an invitation—only basis, a sort of hunting private members’ club. This can only mean one thing: like it or not, hunting is cool. Young people are taking it up, enticed by the element of rebellion and the mystique of what actually happens as hunts attempt to keep within the law.

The word "rebellion" underlined in the last Paragraph refers to ______.

A．betray

B．violation

C．department

D．contravention
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