Early Research in Organic Chemistry

Paragraph 1：The field of chemistry can be roughly divided into organic chemistry, which involves the chemistry of carbon-based compounds, and inorganic chemistry, which deals with all other elements and their compounds. The terms organic and inorganic, as adjectives applied to chemistry, were first used as chemical labels in the 1810s. Before this time, eighteenth-century chemists referred instead to animal, vegetable (plant), and mineral substances, corresponding to the three kingdoms of nature. Of the three, vegetable and animal substances were those produced by and found in living bodies, where their activity was related to the processes of life. Some chemists thought it reasonable to explore those processes chemically, whereas others were convinced that living processes were quite different from the nonliving reactions that they carried out in the laboratory. The former group included the chemists Lavoisier and Berzelius as well as many chemist-pharmacists and chemist-physicians throughout the eighteenth century. The latter group saw the chemistry of living bodies as beyond the reach of chemical investigation. But even those chemists who regarded the substances produced by living nature, by animals and vegetables, as proper subjects for chemical investigation made less progress in organic chemistry than they did in inorganic or mineral chemistry. That is not to say that they did not make significant progress; they successfully established the foundations for a chemistry of plant substances. But the chemistry based on the work of researchers such as Lavoisier and Berzelius was more successful – and succeeded earlier – in the inorganic realm. 

 

 

 

1. According to paragraph 1, which of the following is true of chemists before the 1800s？ 

 

O They had not yet started to study the chemistry of living bodies. 

 

O They mainly studied substances that were associated with the animal kingdom. 

 

O They all studied both organic and inorganic substances. 

 

O They did not yet use the terms organic and inorganic.

 

 

 

2. According to paragraph 1, which of the following correctly characterizes the accomplishments of eighteenth-century researchers who believed that organic substances could be investigated chemically？ 

 

O They were more successful in working with inorganic substances than with organic substances.

 

O They were highly successful in carrying out the investigation of organic substances begun by Lavoisier and Berzelius. 

 

O Their investigations of animal substances were more successful than their investigations of plant substances. 

 

O Their investigations of inorganic substances were less successful than those of researchers who believed that organic substances could not be investigated chemically. 

 

 

 

 

 

 

 

Paragraph 2：There are several reasons why organic chemistry at first made slower progress than inorganic chemistry did. Inorganic elements and compounds can often be isolated in a reasonably pure state. Naturally occurring mineral ores may be a source of pure metals, salts, or oxides. In some parts of the world, sulfur exists in a pure state as an element. Atmospheric gases can be separated; other gases, such as hydrogen, can be obtained in reasonably pure form, for example, by the action of a mineral acid on a metal. The availability of pure substances, whether naturally occurring or produced in the laboratory, is an important prerequisite for the accurate determination of chemical formulas. 

 

 

3. Which of the following elements or compounds is mentioned in paragraph 2 as being found in nature in a pure state？ 

 

O Atmospheric gases other than hydrogen 

 

O Sulfur

 

O Mineral acids 

 

O Hydrogen 

 

 

 

 

 

Paragraph 3：Contrast this availability in the inorganic realm with the substances that are readily available from organic nature. How could chemists extract pure substances from samples of plant and animal tissue? If plant or animal matter is subjected to distillation (purification by successive evaporation and condensation), then, typically, a black residue remains in the distillation vessel, and liquid and gaseous substances are driven off. Chemists attempted to distinguish between different types of plant matter by analyzing the products of distillation quantitatively as well as qualitatively. The solid residue did not vary greatly between different types of vegetable matter, but there were pronounced differences in the properties and quantities of the liquids yielded by distillation, and these differences were carefully probed. Varying the conditions of distillation could produce significant differences in the results, and thus eighteenth-century chemists were able to make important advances by standardizing their analytical procedures. 

 

 

 

4. According to paragraph 3, the products of distillation of different plant substances differ in which TWO of the following respects?

To receive credit, you must select TWO answers. 

 

O The properties of the liquids produced

 

O The amount of solid residue 

 

O The gases that are driven off 

 

O The amount of liquid produced

 

 

 

5. Which of the following can be inferred from paragraph 3 about the distillation of organic substances？ 

 

O When chemists standardized their analytical procedures, there was less difference in the properties and quantities of the liquids they produced by distillation. 

 

O Researchers made progress in analyzing plant substances only after they agreed on which substances they would investigate by distillation.

 

O The products of distillation differed among each other more in their quantitative properties than in their qualitative properties. 

 

O When analytical procedures were standardized, the solid residues left by distillation decreased. 

 

 

 

 

 

Paragraph 4：In spite of these advances, major problems remained. The substances produced by distillation were usually complex mixtures of uncertain purity. There was an added problem: How could chemists know that what they obtained from the destructive distillation of organic matter was present as such in the original matter? Were chemists extracting a substance already present, or did they produce it through their destruction of the original organic tissues? These questions were troubling to chemists. Attempts to minimize the destructive violence of analysis by carrying out distillations at the lowest effective temperature did not solve the problem. 

 

 

 

6. According to paragraph 4, what was one of the problems presented by the distillation of organic matter？ 

 

O It was impossible to control the temperature at which distillation was performed. 

 

O The products of distillation were often more complex and less pure than the original substances. 

 

O The products of distillation were often damaged in the process, making it difficult to identify them with any certainty. 

 

O Chemists could not be certain whether the products of distillation had been present in the original substances.

 

 

7. According to paragraph 4, why did chemists want to carry out distillations at the lowest effective temperature？ 

 

O They were more certain about the impurities in low temperature distillations than those in high temperature distillations. 

 

O They were worried that the substances created by high temperature distillations would also be destroyed by the high temperature. 

 

O They wanted to avoid purifying the complex mixtures of organic substances that were produced by high temperature distillation. 

 

O They were worried that the process of distillation at high temperature might chemically change the substances being distilled.

 

 

 

 

 

Paragraph 5：Suppose, instead, that chemists focused on organic substances that were relatively pure, substances such as fat and blood, not simply a soup brewed from the whole organism. We know today that these are enormously complicated substances, mostly made up of molecules containing unimaginably large numbers of atoms. For this reason and others, the chemistry of organic compounds was more difficult to make sense of than mineral or inorganic chemistry. 

 

 

 

8. The author discusses the composition of fat and blood in order to 

 

O make the point that the chemistry of organic compounds would have progressed more quickly if early chemists had focused on such relatively pure substances 

 

O argue that even if early chemists had focused on such relatively pure substances, organic chemistry would have progressed more slowly than inorganic chemistry

 

O suggest that the main reason organic substances are extremely complicated to analyze chemically is that they are not sufficiently pure 

 

O provide examples of some of the first organic compounds that chemists were able to analyze chemically 

 

 

Paragraph 4：In spite of these advances, major problems remained. The substances produced by distillation were usually complex mixtures of uncertain purity. ■There was an added problem: How could chemists know that what they obtained from the destructive distillation of organic matter was present as such in the original matter? ■Were chemists extracting a substance already present, or did they produce it through their destruction of the original organic tissues? ■These questions were troubling to chemists. Attempts to minimize the destructive violence of analysis by carrying out distillations at the lowest effective temperature did not solve the problem.■

 

 

 

9. Look at the four squares that indicate where the following sentence could be added to the passage. 

 

This made it impossible to determine the properties of any particular substance in the distillation product. 

 

Where would the sentence best fit  Click on a square to add the sentence to the passage. 

 

 

 

 

 

10. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selected THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your choices to the spaces where they belong. To review the passage, click on View Text. 

 

 

 

Answer Choices 

 

O Even chemists who thought that vegetable and animal substances were just as appropriate for chemical analysis as mineral substances made less progress in organic chemistry.

 

O Inorganic substances could be isolated in a sufficiently pure state to allow determination of their chemical formulas, but similar efforts with organic substances ran into problems.

 

O One major problem with distillation was that analysis of the liquids produced revealed different properties and quantities than were revealed in the analysis of the solids. 

 

O Chemists debated whether distillation should first be applied to relatively pure substances such as fat and blood rather than to complex substances such as plant and animal tissue. 

 

O Distillation of plant or animal tissue left residues of uncertain purity, and some chemists questioned whether the products of distillation had been present in the original tissue.

 

O One of the first successes in organic chemistry was the realization that although fat and blood are relatively pure substances, they are made up of extremely complex molecules. 

 

 

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