Unit 4 sources of Unit 4 sources of chemicals chemicals

Unit 4 sources of Unit 4 sources of chemicals chemicals

• Aims and Requirements 1. Mastering New words and terminology;2. Comprehending the text and related backgroun

d knowledge accurately;3. Mastering typical expressions in the text.• Important and Difficult Teaching Points 1. Explanation of the specialized words and termi

nology; 2. Analyzing the structure of the complex sentenc

e; 3. Comprehending and translating the text.

一、 New words and expressions • 3.covalent a. 共价的• covalent bond n.[ 化 ] 共价键• 4.bond• 5.isomerism • cis-trans isomerism 顺反异构• stereo isomerism 立体异构 ( 现

象 )

7.detergent 洗净剂 ; 去污剂 • surfactant 表面活化剂 ; 能减低表面张

力的物质或溶液 ( 如清洁剂 )32.particulate n. 微粒 adj. 微粒的• suspended particulate 悬浮颗粒 ; 悬

浮性粒子

• 34.surface-active agent =surfactant • 38.via=By way of: 经过：• went to Pittsburgh via Philadelphi

a. 经过费城到匹兹堡• 68.decline v. To express polite refus

al.• To slope downward; descend.• They wish that prices would decline.

他们希望物价能下降。

二、 Text Explanation• Qustions:• 1.Compare the sources of inorganic c

hemicals with that of organic chemicals.

• 2.Give an example of the extraction process for processing inorganic chemicals.

• 3.Distinguish between non-renewable resource and renewable resource. And show the relative values of oil in the different forms.

• 4.Evaluate the advantages and disadvantages of the fermentation process.

Question: Compare the sources of inorganic chemicals with that of organic chemicals.

Words: compare tocompare with

Sentences• 1.Even this vast number pales into in

significance [when compared to the number of carbon compounds which is theoretically possible].

• pales into insignificance 变得微不足道

• 2. However, [of the remainder] there are probably several thousands which are of commercial and practical interest.

• are of commercial and practical interest 具有商业和实际应用价值 .

• Be of n. = be adj.

• 3. It might therefore be expected that there would be a large number of sources of these chemicals. Although this is true for inorganic chemicals, surprisingly most organic chemicals can originate from a single source such as crude oil( petroleum ).

• This=there would be a large number of sources of these chemicals

1. Inorganic Chemicals

Question:Give an example of the extraction process for

processing inorganic chemicals.

Words: on one’s own 独自；自己单独地；凭自己力量

in question 上述的

Sentences• 4. If therefore the individual element or ele

ments, say the metal, are required then the extraction process must involve chemical treatment in addition to any separation methods of a purely physical nature.

• in addition to , 除 ... 外还有……

2. Organic Chemicals

Questions:

1. Distinguish between non-renewable resource and renewable resource.

2. Show the relative values of oil in the different forms.

3. Evaluate the advantages and disadvantages of the fermentation process.

Words:1011 读作 ten to the power of eleven, or the

eleventh power of ten, or ten to the eleventh power 。

compete with M for N 与 M 争取 N

barrel 桶 A Barrel (bbl.) of crude contains 42 gallons or 158.8 liters. No one actually ships petroleum in barrels anymore because they are too small, but the term is still used to describe a defined volume.

Sentences• 5. This is a very interesting situation —one which h

as changed over the years and will change again in the future—because technically these same chemicals could be obtained from other raw materials or sources.

• —one which has changed over the years and will change again in the future— 同位语

• 同位语的符号—……… .—; (………….); ,…………….., i.e………..

• 6. The formation of fossil fuels, i.e. oil gas and coal reserves, takes millions of years and once used they cannot be replace. they are therefore referred to as non—renewable resources.

• renewable resources 可再生资源• i.e.=that is

• 7. Clearly alternative energy sources to fossil fuels are now available if we have the will to use them, and we can confidently expect other alternatives to become available in the not too distant future.

• 这里 will 是决心，意志的意思

• 8. It is interesting, and salutary, [to note that as early as 1894 Mendeleyev ( the Russian chemist who developed the Periodic Table ) reported to his government that “oil was too valuable a resource to be burned and should be preserved as a source of chemicals.”]

• It 形式主语

• 9. Some of these processes have been used in the domestic situation for many thousands of years, the best-known example being fermentation of grains to produce alcoholic beverages.

• the best-known example being 最为熟知的例子是

• 10. Indeed up until about 1950 this was the most popular route to aliphatic organic chemicals, since the ethanol produce could be dehydrated to give ethylene, which is the key intermediate for the synthesis of a whole range of aliphatic compounds.

• • key intermediate 关键中间体

• 11. Major disadvantages of fermentation [compared with petrochemical processes ]are , firstly, the time scale, which is usually of the order of days compared to literally seconds for some catalytic petrochemical reactions, and secondly, the fact that the product is usually obtained as a dilute aqueous solution (< 10% concentration ).

• 12. On the other hand particular advantages of fermentation methods are (that they are very selective and that some chemicals which are structurally very complex, and therefore extremely difficult to synthesize, and/or require a multi-stage synthesis, are easily made.)

• 13. Provided that the immense practical problems associated with the rapidly developing field of genetic engineering, [where micro-organisms such as bacteria are ‘tailor-made’ to produce the required chemical], can be overcome, then the interest in fermentation methods will be very considerable.

• Provided that =if 如果 , 只要 , 倘若

The advantages and disadvantages of the fermentation process:

Advantages Disadvantages

1. high selectivity higher raw

material costs

2. structurally very high separation and

complex chemical purification costs

3. renewable resources difficult and expensive

transportation 4. long time scale

三、 Exercises• P42Exercise 1Exercise 2

科技术语构成（ 1）

一、合成法1. 名词＋名词 octane number

limitation reaction

2. 形容词＋名词 biological degradation

molecular formula

3. 动名词＋名词 alkylating reaction

antibonding orbital

4. 过去分词＋名词 saturated hydrocarbon

branched chain

5. 名词＋动名词 oxygen-containing

6. 名词＋过去分词 hand-made

7. 名词＋形容词 snow-white

paper-thin

8. 形容词＋形容词 red-hot

dark-blue

light-yellow