问题 实验题

(15分)某探究小组废弃的印刷线路板(含Cu、A1少量Au、Pt等金属的混合物)回收Cu并制备硫酸铝晶体[A12(SO43.18H2O],设计路线如下:

(1)过滤时所需要的玻璃仪器有玻璃棒、                  

(2)实验时需对滤渣2进行洗涤,判断洗涤是否干净的实验操作方法是           

(3)为确定加入铁粉的量,实验中需测定滤液1中Cu2+的量。实验操作为:除去H2O2;准确量取一定体积滤液1于带塞锥形瓶中,加水稀释,调节溶液pH=3-4,加入过量KI-淀粉溶液,用Na2S2O3标准溶液滴定至终点。上述过程中反应的离子方程式:

①滴定管在注入Na2S2O3标准溶液之前,要先用蒸馏水洗净,再用      

②滴定终点观察到的现象为            

③若滴定前溶液中的H2O2没有除尽,所测定的含量将会         (填“偏高”、“偏

低”或“不变”)

(4)由滤液2制取硫酸铝晶体,探究小组设计了如下二种方案:

甲:

乙:

①操作③的实验步骤依次为:蒸发浓缩:                 、洗涤。

②从原子利用率角度考虑,          方案更合理。(填“甲”或“乙”)

(5)他们查阅了资料,认为通过先氧化、再调节溶液pH也可将滤液2中的除去。下表列出了几种离子生成氢氧化物沉淀的pH(开始沉淀的pH按金属离子浓度为1.0mo1.L-1计算)。

 开始沉淀的pH沉淀完全的pH
Fe3+1.13.2
Fe2+5.88.8
A13+3.85.2
①氧化需加入H2O2而不用C12的原因是                 

②调节溶液pH约为               

答案

(1)漏斗、烧杯(2分)

(2)取最后一次的洗涤液,加入氯化钡溶液和稀盐酸无白色沉淀出现(,说明洗涤干净)(或其他合理答案)(2分)

(3)①Na2S2O3标准溶液润洗2~3次(1分)

②溶液蓝色恰好褪去(且半分钟内不恢复)(1分)③偏高(2分)

(4)①冷却结晶(1分)过滤(1分)②甲(1分)

(5)①不引入杂质,对环境无污染(2分)②3. 2~3. 8(答3.5等也可以)(2分)

(1)过滤时所需要的玻璃仪器有玻璃棒、漏斗和烧杯。

(2)沉淀变慢吸附的有SO42,据此可以检验,即取最后一次的洗涤液,加入氯化钡溶液和稀盐酸无白色沉淀出现。

(3)①滴定管在装入标准液之前,除了需要蒸馏水洗涤外,还需要用标准液润洗,即还需要用Na2S2O3标准溶液润洗2~3次。

②由于碘能和淀粉发生显色反应,据此可以判断终点,即溶液蓝色恰好褪去(且半分钟内不恢复)。

③由于双氧水也能氧化碘离子,所以消耗的标准液偏多,测定结果偏高。

(4)①从溶液中得到晶体的方法是蒸发浓缩、冷却结晶、过滤、洗涤。

②方案乙中,还生成硫酸钠,原子利用率低。所以甲方案更合理。

(5)①双氧水的还原产物是水,不引入杂质,对环境无污染。

②根据表中数据可知,氢氧化铝开始沉淀时的pH是3.8,所以范围是3. 2~3. 8。

完形填空

The World  Health Organization(WHO)  says there has been a sharp increase in the number of children in developing countries who weigh too much.  In African countries, the WHO says the number of overweight or obese children is two times as  high  as it was 20 years ago.

Around the world, about 43 million children under the age of five were overweight in 2011. Doctors use height, weight and age to measure whether a person is underweight, normal, or obese.                              

Overweight children are more likely to become overweight or obese adults.  The condition can lead to serious health problems like diabetes, heart disease and stroke.

Francesco Branca , director of the WHO Department of Nutrition for Health and Development, says people are eating manufactured or processed food more often, which often has a high sugar. fat and salt content.  Another reason of gaining weight is the city lifestyle.  They travel in cars or other vehicles more than on foot, and have less physical activities in general.

Mr Branca says reducing the number of overweight children will not be easy.  He says the goal is difficult to meet even in wealthy countries.

The WHO has some basic solutions for individuals(个人) : to lower your in-take of fat ,sugar, salt and processed food, eat more fruit and vegetables, and increase physical activity .These actions are especially important for children and governments should concern providing vitamin for children .

Reducing the number of overweight children will not be easy.  The goal is difficult to meet even in wealthy countries. Educational campaigns about problems linked to obesity would also help. Food manufactures must balance quality and taste with the dangers of sugar, fat and salt.

The current goal of the WHO's World Health Assembly is to prevent an increase in the percentage of overweight children during the next twelve years.

小题1:What's the main idea of the passage?(No more than 15 words)

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小题2:What is the meaning of the underlined word "obese" in Paragraph 2?(No more than two words)

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小题3:What diseases can overweight or obesity lead to?(No more than 10 words)

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小题4:Why do people put on weight easily? (No more than 12 words)

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小题5:If you are overweight or obese, what should you do? (No more than 20 words)

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