READING COMPREHENSION

12 Study the text Lab Safety Rules and underline the expressions you are not familiar with. Can you guess their meaning from the context? If not, consult the dictionary.

13 Did any of the rules surprise you?

GENERAL GUIDELINES       CLOTHING   ACCIDENTS AND INJURIES   HANDLING CHEMICALS   1. When first entering a science room, do not touch any equipment, chemicals, or other materials in the laboratory area until you are instructed to do so. 2. Never work alone in the laboratory. No student may work in the science classroom without the presence of the instructor. 3. Perform only those experiments authorized by your teacher. Carefully follow all instructions, both written and oral. Unauthorized experiments are not allowed.   4. Do not eat food, drink beverages, or chew gum in the laboratory. Do not use laboratory glassware as containers for food or beverages.   5. Be prepared for your work in the laboratory. Read all procedures thoroughly before entering the laboratory. Never fool around in the laboratory.   6. Always work in a well-ventilated area. 7. Observe good housekeeping practices. Work areas should be kept clean and tidy at all times.   8. Proceed with caution at all times in the laboratory. Notify the teacher immediately of any unsafe conditions you observe.   9. Dispose of all chemical waste properly. Never mix chemicals in sink drains. Sinks are to be used only for water. Check with your teacher for disposal of chemicals and solutions.   10. Labels and equipment instructions must be read carefully before use. Set up and use the equipment as directed by your teacher.   11. Keep hands away from face, eyes, mouth, and body while using chemicals or lab equipment. Wash your hands with soap and water after performing all experiments   12. Experiments must be personally monitored at all times. Do not distract other students or interfere with the laboratory experiments of others. 13. Know the locations and operating procedures of all safety equipment including: first aid kit(s) and fire extinguisher. Know where the fire alarm and the exits are located. 14. Know what to do if there is a fire drill during a laboratory period; containers must be closed, and any electrical equipment turned off.     15. Any time chemicals, heat, or glassware are used, students will wear safety goggles. NO EXCEPTIONS TO THIS RULE!   16. Contact lenses may be not be worn in the laboratory.     17. Dress properly during a laboratory activity. Long hair, dangling jewellery, and loose or baggy clothing are a hazard in the laboratory. Long hair must be tied back, and dangling jewellery must be secured. Shoes must completely cover the foot. No sandals allowed on lab days.     18. A lab coat or smock should be worn during laboratory experiments.     19. Report any accident (spill, breakage, etc.) or injury (cut, burn, etc.) to the teacher immediately, no matter how trivial it seems. Do not panic.   20. If you or your lab partner is hurt, inform the teacher immediately. Do not panic.   21. If a chemical splashes in your eyes or on your skin, immediately flush with running water for at least 20 minutes.     22. All chemicals in the laboratory are to be considered dangerous. Avoid handling chemicals with fingers. Always use tweezers. When making an observation, keep at least 1 foot away from the specimen. Do not taste, or smell any chemicals. If you need to identify a smell, cup your hand and waft.   23. Check the label on all chemical bottles twice before removing any of the contents. Take only as much chemical as you need.   24. Never return unused chemicals to their original container.   25. Never remove chemicals or other materials from the laboratory area.

TEAM WORK

14 Work in pairs or small groups and decide which of the rules are of the utmost importance. Make a TOP TEN list and reason your choice. Then report to the rest of the class.

15 Make a summary of the most important laboratory safety rules concerning the following facts:

- dress code for a laboratory worker

- refreshment during the lab period

- working with chemicals

- working with hot glassware

- what to do in case of injury

- what to do in case of fire

16 Read the Chemistry Poem. Do you know any poem, joke or anecdote about chemists, chemistry or labs?

Chemistry Poem

Poor Willie worked in chem lab. Poor Willie is no more.

For what he thought was H₂O was H₂SO₄!

FOLLOWING INSTRUCTIONS

17 Read the instructions on how to produce aspirin.

How to Make Aspirin - Acetylsalicylic Acid - Introduction and History

1. Accurately weigh 3.00 grams of salicylic acid and transfer to a dry Erlenmeyer flask. If you calculate actual and theoretical yield, be sure to record how much salicylic acid you actually measured.

2. Add 6 mL of acetic anhydride and 5-8 drops of 85% phosphoric acid to the flask.

3. Gently swirl the flask to mix the solution. Place the flask in a beaker of warm water for 15 minutes.

4. Add 20 drops of cold water dropwise to the warm solution to destroy the excess acetic anhydride.

5. Add 20 mL of water to the flask. Set the flask in an ice bath to cool the mixture and speed crystallization.

6. When the crystallization process appears complete, pour the mixture through a Buchner funnel.

7. Apply suction filtration through the funnel and wash the crystals with a few milliliters of ice cold water. Be sure the water is near freezing to minimize loss of product.

8. Perform a recrystallization to purify the product. Transfer the crystals to a beaker. Add 10 mL of ethanol. Stir and warm the beaker to dissolve the crystals.

9. After the crystals have dissolved, add 25 mL of warm water to the alcohol solution. Cover the beaker. Crystals will reform as the solution cools. Once crystallization has started, set the beaker in an ice bath to complete the recrystallization.

10. Pour the contents of the beaker into a Buchner funnel and apply suction filtration.

11. Remove the crystals to dry paper to remove excess water.

12. Confirm you have acetylsalicylic acid by verifying a melting point of 135°C.

VOCABULARY

yield - the quantity of a product formed by the interaction of two or more substances

swirl - to move around or along with a whirling motion

excess - the fact of exceeding something else in amount or degree

suction - to draw out or remove by aspiration

loss - something that is lost

confirm - to acknowledge with definite assurance

verify - to prove the truth of, as by evidence or testimony; confirm

18 Make a list of all the items of laboratory equipment you need for this experiment.

19 Match the verbs describing the process with the nouns.

transfer excess water

mix the crystals

remove a funnel

dissolve to a flask

pour through loss of product

minimize the solution

20 Write down the KEY WORDS from each instruction. Then try to cover the text and reconstruct the procedure using your key words.

WRITING

21 Choose one of the experiments you really performed in the laboratory and write down the instructions of the procedure. (minimum: 10 steps)

LEXICAL EXERCISES

22 Look again at the instructions for making aspirin in exercise 17, namely steps 8 and 9 containing the words recrystallization and reform. What is the meaning of the prefix re- in those words?

23 A Use 8 of the following prefixes to fill the gaps.

dis- en- im- inter- mono- nano- pre- semi- ultra- un- micro-

­_____cellular space serves for gas to be exchanged between cells.

_____capsulated drugs are used for targeted delivery, i.e. the capsule dissolves and releases its contents when it reaches the required location.

_____tubes have a diameter smaller than 200 x 10⁹ meters.

_____structure is the detailed structure of biological specimen, such as a cell, tissue, or organ, that can be observed by electron _____scopy.

Often it is impossible to _____determine the specific problems that researches will meet during their laboratory work.

_____basic acids, such as HCl or HNO₃, are acids that have only one hydrogen ion to donate to a base in an acid-base reaction.

Trans fatty acid is commonly produced by partial hydrogenation of _____saturated fatty acid vegetable oils.

B Explain the meaning of the prefixes.

C Make words with the remaining 3 prefixes and use them in sentences.

24 Work in pairs.

Student A: Fill in table A

Student B: Fill in table B on the Activity Sheet (end of Unit 3)

If you can´t remember anything that would fit in the Example column, your partner will define the word for you to guess.

Table A

25 Study the Common Affixes section of the Grammar File.

26 Fill in the table:

Date: 2015-01-12; view: 2650