问题 问答题

某有机物完全燃烧时只生成二氧化碳与水,取2.3g 该有机物完全燃烧,将产物通过浓硫酸,浓硫酸增重2.7g,继续将产物通过碱石灰,碱石灰增重4.4克,已知该有机物相对分子质量为46.

(1)求该有机物的分子式;

(2)写出该有机物可能的同分异构体的结构简式.

答案

(1)使浓硫酸增重可知水的质量为2.7g,可计算出n(H2O)=

2.7g
18 g/mol 
=0.15 mol,n(H)=0.3 mol,m(H)=0.3g;使碱石灰增重4.4g,可知二氧化碳质量为4.4g,n(C)=n(CO2)=
4.4g
44g/mol 
=0.1 mol,m(C)=1.2g,m(C)+m(H)=1.5g,因有机物的质量为2.3g,所以有机物中氧的质量为0.8g,n(O)=
0.8g
16g/mol
=0.05mol,

n(C):n(H):n(O)=0.1mol:0.3mol:0.05mol=2:6:1,即实验式为C2H6O,设分子式为(C2H6O)n,又A的相对分子质量为46,解得:n=1,

答:有机物的分子式为:C2H6O;

(2)C2H6O的同分异构体的结构简式为:

答:该有机物可能的同分异构体的结构简式为

问答题 论述题
阅读理解

Today, among people everywhere, there is an increasing awareness and worry about the steady growth in the world’s population.A recent survey conducted by the United Nations Fund for Population Activities (UNFPA) reported that this growth will continue until the end of the next century.For developing countries alone, the annual average population growth is, at present, 4.6% compared to 2.0% for developed countries.At this rate, the world’s population will reach 10.2 billion by the turn of the 21st century.With the growth in population is the problem of food security… the guarantee of a steady supply of food.The unstoppable growth in population justifies the Malthusian Doctrine that population of a region will continue to grow unless checked, and this is of course alarming since it will inevitably lead to food shortages of considerable proportions.

Our forests are an abundant source of food and fuel, two items essential in sustaining life.Above 30% of the world’s land surface is covered by such forests.In Asia alone, more than two billion people depend heavily on forest products for their subsistence and survival.To maintain a reasonable balance between population growth and food supply, this natural source of life — sustaining food and fuel must be conserved and protected from its worst enemy — man himself.It is appalling (令人震惊的) to note that in many developing countries, which are themselves heavily hit by population-food imbalance, governments approve the cutting down of forests to meet their immediate needs for saleable timber, and also for agricultural land.Often the cutting down and burning of forests is conducted with total abandon owing to the absence of sound forestry techniques and management.At the rate tropical forests are now being cleared each year, the world’s tropical forests will be completely destroyed within the next 100 years.

In order to maintain food security for the world’s population, the Food and Agricultural Organization of the United Nations (FAO) has launched a campaign aimed at ensuring food supply, maximizing stability in the flow of this supply and ensuring access to it by all.Forestry, according to the FAO, plays a vital role in making it possible to fulfill all its three objectives.Its most important role is that of conserving soil and water.Trees provide natural protection against soil erosion (侵蚀) by absorbing the excess water brought by heavy rains.

1.The first paragraph tells us that ____.

A.the flow of food supply is the result of population increase.

B.the world population has reached the 10-billion mark.

C.the problem of population growth has caused considerable alarm in a few countries.

D.the problem of food supply goes hand-in-hand with population increase.

2.The Malthusian Doctrine presents ____ as far as world population is concerned.

A.an optimistic view of the future     B.a pessimistic outlook for the future

C.an encouraging picture          D.an indifferent picture

3.In this context, “this natural source of life — sustaining food and fuel” (in Paragraph 2) refers to ____.

A.the flow of food supply           B.forests

C.woodland products               D.man’s worst enemy

4.The three objectives of the FAO can be replaced by ____.

A.stopping population growth       B.increasing food production

C.achieving food security          D.ensuring maximum utilization of forests