问题 问答题

锂离子电池的广泛应用使回收利用锂货源成为重要课题:某研究性学习小组对废旧锂离子电池正极材料(LiMn2O4、碳粉等涂覆在铝箔上)进行资源回收研究,设计实验流程如下 

(1)第②步反应得到的沉淀X的化学式为______.

(2)第③步反应的离子方程式是______.

(3)第④步反应后,过滤Li2CO3所需的玻璃仪器有______.若过滤时发现滤液中有少量浑浊,从实验操作的角度给出两种可能的原因:______、______.

(4)若废旧锂离子电池正极材料含LiNB2O4的质量为18.1g第③步反应中加入20.0mL3.0mol•L-1的H2SO4溶液.定正极材料中的锂经反应③和④完全为Li2CO3,剩至少有______Na2CO3参加了反应.

答案

第一步就是铝溶解在氢氧化钠溶液中(注意LiMn2O4不溶于水)生成四羟基合铝酸钠,即滤液的主要成分,第二步就是四羟基合铝酸钠与二氧化碳反应生成氢氧化铝沉淀和碳酸氢钠的过程,第三步是LiMn2O4在酸性环境下能被空气中的氧气氧化发生的氧化还原反应,得到的滤液中有生成的硫酸锂,可能有过量的硫酸,最后一步加入碳酸钠之后所得的滤液主要成分为硫酸钠;

(1)四羟基合铝酸钠与过量二氧化碳反应得产物是Al(OH)3沉淀和碳酸氢钠,故答案为:Al(OH)3

(2)在酸性环境下,LiMn2O4能被空气中的氧气氧化,离子方程式为:4 LiMn2O4+O2+4H+=4Li++8MnO2+2H2O,故答案为:4 LiMn2O4+O2+4H+=4Li++8MnO2+2H2O;

(3)过滤所用玻璃仪器有:漏斗、玻璃棒、烧杯;过滤时发现滤液中有少量浑浊,原因可能有:滤纸破损、滤液超过滤纸边缘等,故答案为:漏斗、玻璃棒、烧杯;滤纸破损、滤液超过滤纸边缘

(4)根据LiMn2O4~0.5H2SO4~Li+得18.1gLiMn2O4即0.1molLiMn2O4消耗硫酸的量为0.05mol,故硫酸有剩余,剩余的硫酸和生成的Li+共消耗碳酸钠0.05mol,即5.3g,故答案为:5.3g.

单项选择题

The differences in living standards around the world are vast In 1993, the average American had an income of about $25,000. In the same year, the average Mexican earned $7,000, and the average Nigerian earned. $1,500. Not surprisingly, this large variation in average income is reflected in various measures of the quality of life. Changes in living standards over time are also large. In the United States, incomes have historically grown about 2 percent per year (after adjusting for changes in the cost of living). At this rate, average income doubles every 35 years. In some countries, economic growth has been even more rapid. In Japan, for instance, average income has doubled in the past 20 years, and in South Korea it has doubled in the past 10 years.

What explains these large differences in living standards among countries and over time The answer is surprisingly simple. Almost all variation in living standards is attributable to differences in countries’ productivity—hat is, the amount of goods and services produced from each hour of a worker’s time. In nations where workers can produce a large quantity of goods and services per unit of time, most people enjoy a high standard of living; in nations where workers are less productive, most people must endure a more meager existence. Similarly, the growth rate of a nation’s productivity determines the growth rate of its average income.

The fundamental relationship between productivity and living standards is simple, but its implications are far-reaching. If productivity is the primary determinant of living standards, other explanations must be of secondary importance. For example, people might think that labor unions or minimum-wage laws contributed to the rise in living standards of American workers over the past century. Yet the real hero of American workers is their rising productivity.

The relationship between productivity and living standards also has great implications for public policy. When thinking about how any policy will affect living standards, the key question is how it will affect our ability to produce goods and services. To improve living standards, policymakers need to raise productivity by ensuring that workers are well educated, have the tools needed to produce goods and services, and have access to the best available technology.

Which of the following countries has enjoyed the fastest economic growth in history().

A. Mexico.

B. The United States.

C. Japan.

D. South Korea.

填空题