问题 填空题

某烃A 0.2 mol 在氧气中完全燃烧后,生成CO2、H2O各1.2 mol。试回答下列问题:

(1)烃A的分子式为            

(2)若取一定量的烃A完全燃烧后,生成CO2和H2O各3 mol,则有       g烃A参加了反应,燃烧时消耗标准状况下的氧气          L。

(3)若烃A不能使溴水褪色,但在一定条件下能与氯气发生取代反应,其一氯取代物只有一种,则烃A的结构简式为                 

(4)若烃A能使溴水褪色,在催化剂作用下,与H2加成,其加成产物经测定分子中含有4个甲基,则烃A可能的结构简式有                                         

答案

⑴C6H12(1分)

⑵42 (1分) 100.8 (1分)

(2分)

⑷(CH3)3CCH=CH2、CH2=C(CH3)CH(CH3)2、(CH3)2C=C(CH3)2  (3分)

题目分析:(1)烃A 0.2 mol 在氧气中完全燃烧后,生成CO2、H2O各1.2 mol,折算成1mol的烃则生成CO2、H2O各6mol,所以该烃的分子式为C6H12

(2)1mol的烃A则生成CO2、H2O各6mol,所以生成CO2和H2O各3 mol,则消耗烃A0.5mol,其质量是0.5mol×84g/mol=42g,根据烃A燃烧的化学方程式,计算消耗氧气4.5mol,标准状况下的体积是4.5mol×22.4L/mol=100.8L;

(3)烃A不能使溴水褪色,说明分子中不存在碳碳双键,所以为环状结构;一定条件下能与氯气发生取代反应,其一氯取代物只有一种,所以烃A为环己烷,结构简式为

(4)烃A能使溴水褪色,说明分子中存在碳碳双键;与H2加成,其加成产物经测定分子中含有4个甲基,说明分子中存在2个取代基甲基,所以主链为4个C原子、2个取代基甲基的烯烃A有3种,结构简式分别为(CH3)3CCH=CH2、CH2=C(CH3)CH(CH3)2、(CH3)2C=C(CH3)

单项选择题
阅读理解

阅读理解

     There are several advantages in planting trees: they firm the soil, soak(渗透) up extra water and take

carbon dioxide out of the atmosphere.However, it now turns out that planting trees could add to global

warming.We all know that tree roots do a great job of keeping soil firmly on the ground and out of the

wind's power.The problem is that some of the dust clouds play an important part in soaking up carbon

dioxide.

     Huge dust storms blow out over the oceans from dry parts of North Africa and Central Asia.Tons of

dust are lifted and left as a thin film over the ocean surface.

     Dust from China is carried east and left in the Pacific Ocean.If a tree?planting programme there is

successful and the dust supply reduced, the net result may be that less carbon dioxide gets locked away

in the ocean.

     Andy, an environmental scientist has spent the past few years studying dust and says his work shows

clearly the complexity of the system.For this reason the need is to focus on cutting carbon dioxide giving

off rather than doing anything else.

     Robert, an American scientist, has shown that when native grassland areas are invaded by trees,

carbon is lost from the soil."We are studying why the soil carbon disappears, but one theory is that trees

do a lot more of their growing above ground compared to grass, so less carbon goes directly into the soil

from trees." said Robert.

     In wet areas of the world, the gain from trees absorbing carbon dioxide above ground seems to be

outweighed by the loss of carbon from the soil below ground.

     Countries that plan to fight against global warming by planting trees may have to think again.Solutions

to environmental problems are often more complex than they first appear, and understanding the Earth's

climate is a very great challenge.

1. People usually hold the opinion that________.

A. huge dust storms can destroy carbon dioxide

B. planting trees could reduce global warming

C. huge dust storms can destroy the oceans on the Earth

D. planting trees is the only way to control huge dust storms

2. Andy, an environmental scientist, believes that________.

A. environmental problems are more complex than expected

B. trees shouldn't have been planted in dry places

C. dust plays a more important part than trees

D. carbon dioxide is harmful to everything

3. Robert's experiment proves that________.

A. trees absorb more carbon than grass

B. carbon can turn grass into dust

C. less carbon can make trees grow faster

D. grassland areas should be covered by forests

4. The best title for this passage is "________".

A. The importance of planting trees

B. The dust clouds soak up carbon dioxide

C. Is it really useful to plant trees to reduce global warming?

D. Why the soil carbon disappears