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问题 计算题

（6分）张南同学想测定赤铁矿中氧化铁的质量分数，做法如下，请回答下列问题。

（1）配制稀硫酸。

①配制200g 19.6%的稀硫酸，需要98%的浓硫酸的体积是        ；

②下图实验过程中出现操作的错误是                                        。

(2)将赤铁矿粉末，用稀硫酸溶解，反应的化学方程式是                      ；

(3)取20g的赤铁矿粉末恰好与l50g的19.6％的稀硫酸完全反应，求解生成硫酸铁质量(x)的比例式为                    ；

(4)此赤铁矿中氧化铁的质量分数为                             ；

(5)向反应后所得溶液中加入34g水，则所得溶液溶质的质量分数是           

答案

（1）① 26mL   ②读数的方式错误；浓硫酸和水加入的顺序颠倒。

（2）Fe2O3+3H2SO4=Fe2（SO4）3+3H2O

（3）294/400=29.4g/x

（4）80%

（5）20%

（1）①需要98%的浓硫酸的体积是=200g×19.6%÷98%÷1.6g/cm3=25mL．

故答案为：25mL；②用量筒量取液体读数时视线要与凹液面的最低处保持水平，稀释浓硫酸时要先加水，然后将浓硫酸注入水中，所以答案为：读数的方式错误；浓硫酸和水加入的顺序颠倒

（2）赤铁矿的主要成分为三氧化二铁，三氧化二铁与硫酸反应生成硫酸铁和水；故答案为：Fe2O3+3H2SO4=Fe2（SO4）3+3H2O；

（3）设生成硫酸铁质量x

Fe2O3+3H2SO4=Fe2（SO4）3+3H2O

294   400

150g×19.6%  x

故答案为：

294：400=50g×19.6%：x；

（4）设氧化铁的质量为y

Fe2O3+3H2SO4=Fe2（SO4）3+3H2O

160     294

Y      150g×19.6%

160：294= Y：150g×19.6%

y=16g

赤铁矿样品中氧化铁的质量分数为：16g/20g×100%=80%．

故答案为：80%；

（5）向反应后所得溶液中加入34g水，则最终所得溶液中溶质的质量分数是20%．

故答案为：20%

选择题

作为一种清洁能源，风能的开发越来越受到人们的关注。读“陆地与海上风速剖面比较图”，据此完成题。

小题1:科技的发展对能源的影响是

①能源的种类不断增加               ②能源的消费结构日趋多样化

③非可再生能源变为可再生能源       ④各种能源的蕴藏量不断增加

A．①②

B．①②③

C．①②④

D．①②③④小题2:据图判断，为了有效利用风能发电，应使安装发电装置的风塔高度

A．海洋高于陆地

B．陆地高于海洋

C．海洋和陆地上相同

D．据图无法判断
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单项选择题

Pupils at GCSE are to be allowed to abandon learning traditional "hard" science, including the meaning of the periodic table, in favour of "soft" science such as the benefits of genetic engineering and healthy eating. The statutory requirement for pupils to learn a science subject will be watered down under a new curriculum introduced next year. There will be no compulsion to master the periodic table—the basis of chemistry—nor basic scientific laws that have informed the work of all the great scientists such as Newton and Einstein. The changes, which the government believes will make science more "relevant" to the 21st century, have been attacked by scientists as a "dumbing down" of the subject. In June the government had to announce financial incentives to tackle a shortage of science teachers. Academics have estimated that a fifth of science lessons are taught by teachers who are not adequately qualified.
Most children now study for the double-award science GCSE, which embraces elements of biology, chemistry and physics. This GCSE will be scrapped and ministers have agreed that from next year all 14-years-old will be required to learn about the general benefits and risks of contemporary scientific developments, in a new science GCSE. A harder science GCSE will also be introduced as an optional course. One expert involved in devising the new system believes it will halve the number of state school pupils studying "hard" science. Independent schools and more talented pupils in the state sector are likely to shun the new papers in favour of the GCSEs in the individual science disciplines of physics, chemistry and biology. These will continue to require pupils to achieve an understanding of scientific principles.
The new exams were devised after proposals by academics at King’s College London, who told ministers that science lessons were often "dull and boring" and required pupils to recall too many facts. Their report said: "Contemporary analyses of the labour market suggest that our future society will need a larger number of individuals with a broader understanding of science both for their work and to enable them to participate as citizens in a democratic society. "
However, Professor Colin Blakemore, chief executive of the Medical Research Council, warned that reducing the "hard" science taught in schools would create problems. "I can understand the government’s motives," he said. "There is a crisis of public confidence in science which is reducing the progress of policy on such issues as nuclear energy and stem cell research. But sixth-formers are already arriving at university without the depth of knowledge required." Others endorse the new approach. Results at North Chadderton upper school in Oldham—one of 80 schools piloting the new "softer" GCSE, named Twenty first Century Science have improved. Martyn Overy, the head of science, said: "The proportion getting higher grades in science went up from 60% to 75%. The course kept their interest, had more project work and was more relevant. "
As part of their course, the pupils studied what kind of food they needed to keep fit and healthy. Critics say it is only marginally more demanding than following the advice of Nigella Lawson, the television chef, who promotes the benefits of eating proper meals instead of snacking from the fridge. Some science teachers are skeptical. Mo Afzal, head of science at the independent Warwick school, said. "These changes will widen the gap between independent and state schools. Even the GCSE that is designed for those going on to A-level science is not as comprehensive as the test it replaces." John Holman, director of the National Science Learning Centre at York University, who advised the government on the content of the new system, said: "The new exam is not dumbing down. The study of how science works is more of a challenge than rote learning. "

SCIENCE LESSONS


Out

　　　　　　　　　　　　　　　　

In


Periodic table______ The drugs debate______
Ionic equations______ Slimming issues______
Structure of the atom______ Smoking and health______
Boyle’s law______ IVF treatment______
Ohm’s law______ Nuclear controversy______

The phrase "watered down" in the sentence "The statutory requirement for pupils to learn a science subject will be watered down under a new curriculum introduced next year. " (para. 1) can best be replaced by which of the following

A．removed completely

B．reduced much in force

C．revised greatly

D．reinforced to a certain extent
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