- •Lead-in
- •II. Read the text and find the answers to the questions above. Text a
- •Introduction into chemistry
- •1. Define if the sentences are true (t) or false (f).
- •2. Find in the text English equivalents to the following Russian words and word- combinations.
- •3. Find in the text the synonyms for the following words.
- •4. What notions do these groups of key words describe?
- •5. Match the words from two columns to make word-combinations. Make up your own sentences with these phrases.
- •6. Match the beginnings and the endings of the sentences.
- •Text b fundamental concepts of chemistry
- •1. Read the text again paying attention to the words in bold. Make up your own sentences with these words.
- •2. Match the words from the box with the pictures.
- •3. Translate the sentences into English without using a dictionary.
- •4. Look at the picture and comment on it from the point of view of chemistry.
- •5. Look through the text and find the main concepts of chemistry. Complete the chart. Give a definition for each concept and compare it with the definitions of your groupmates.
- •6. Read the following word-combinations.
- •Ionic bonds
- •7. Watch the video 'What is an Atom?'. Fill in the gaps in the following sentences.
- •8. Prepare the reports upon one of the following topics:
- •9. Surf the Internet. Find the information about new chemical sub-disciplines which have emerged in recent years. Make presentations. Use some useful expressions from the Appendix 1.
- •I . Lead-in
- •II. Read the text and find the answers to the questions above. Text a
- •Inorganic chemistry
- •Ores and Alloys
- •Chemical Bonding
- •Concept of Acids and Bases
- •Coordination Chemistry
- •Nuclear and Radioactivity
- •1. Define if the sentences are true (t) or false (f).
- •2. Find in the text English equivalents to the following Russian words and word-combinations.
- •3. Match the term on the left with the definition on the right.
- •4 . Match the words from two columns to make word-combinations. Make up your own sentences with these phrases.
- •5. Put the words in the right word order to make sentences.
- •With, Coordination, complexes, the, of, chemistry, deals, study.
- •6. Fill in the gaps using the words and word-combinations given below in the correct form. Translate the sentences.
- •7. Write down the words you associate with the term “inorganic chemistry”. Compare your words with the words of your groupmates.
- •Inorganic chemistry
- •8. Render the essence of each paragraph in one sentence. Use these sentences to present the summary of the text for your groupmates.
- •III. Read the following text. What is the meaning of the words in bold? text b types of inorganic chemical reactions
- •1. Practice in reading chemical formulas and equations in the text (see the rules in Appendix 4).
- •2. Each column contains a category and some terms listed under it. Cross out the term that does not fit in each category.
- •3. Define the type of inorganic chemical reaction.
- •4. Look at the picture and comment on it from the point of view of chemistry.
- •5. Read the following words and word-combinations.
- •Uses of sulphuric acid
- •5. Watch the video 'Sulphuric Acid Production'. Decide if the sentences are true (t) or false (f).
- •6. Explain the following words and word-combinations in English.
- •7. Make up the sentences of your own with the words in bold. Provide your own examples of combustion reactions and precipitation reactions.
- •8. Ask different types of questions to the text and answer your groupmates' questions.
- •9 . Prepare a report upon one of the following topics:
- •Lead-in
- •II. Read the text and find the answers to the questions above. Text a analytical chemistry
- •1. Define if the sentences are true (t) or false (f).
- •2. Find in the text English equivalents to the following Russian words and word-combinations.
- •3. Fill in the gaps using the word-combinations given below. Translate the sentences.
- •4. Match the term on the left with the definition on the right.
- •5 . Match the words from two columns to make word-combinations. Make up your own sentences with these phrases.
- •6. Put the words in the right order to make questions. Then ask the questions to your groupmates.
- •7. Write down the words you associate with the term “analytical chemistry”. Compare your words with the words of your groupmates.
- •Analytical chemistry
- •8. Make up the plan of the text and summarize information.
- •III. Read the following text. What is the meaning of the words in bold? text b titration
- •1. Match the following terms with their definitions:
- •2. Translate the sentences into English without using a dictionary.
- •3. Read the following text about acid-base titration and unscramble the letters in the brackets to find the correct word. Translate the text.
- •4. Rewrite the sentence so that it contains the word in capitals.
- •5. Look at the picture and comment on it from the point of view of chemistry.
- •6. Ask different types of questions to the text “Titration” and answer your groupmates' questions.
- •7. Look through the text b. Make up the sentences of your own with the words in bold.
- •8. Read the text. Which pH indicator is the most acidic? Which one is the most basic? Make up the graph showing the efficient pH range of these indicators. PH indicators
- •Universal pH Indicator
- •Natural pH Indicator
- •Unit 4. Organic chemistry
- •I. Lead-in.
- •II. Read the text and find the answers to the questions above. Text a organic chemistry
- •1. Define if the sentences are true (t) or false (f).
- •2. Find in the text English equivalents to the following Russian words and word-combinations.
- •3. Fill in the gaps in the following sentences using the text above. Translate the sentences.
- •4. What notions do these groups of key words describe?
- •5. Make up the questions using the words given and 3 questions of your own. Present them in the form of a dialogue with your partner.
- •6. Read the 10 facts about carbon and match the two parts of each statement. What is the meaning of the words in bold?
- •7 . Make a short report about the importance of carbon in organic chemistry using the information above. If necessary, use the key word-combinations:
- •Organic chemistry
- •III. Read the following text. What is the meaning of the words and word-combinations in bold? text b classification of organic compounds
- •1. Match the words from the box with the pictures.
- •2. Translate the sentences into English without using a dictionary.
- •3. What are the scientific contributions made by the following organic chemists? Tell your partner about them. If necessary, use the Internet.
- •4. Look at the picture and comment on it from the point of view of chemistry. Say what classes these organic compounds belong to.
- •5. Read the following text and choose the correct word among suggested to fill in the gaps.
- •3 Accidental organic chemistry discoveries
- •Penicillin
- •Saccharin
- •Mauveine
- •6. Watch the video ‘Are artificial sweeteners really safe?’ Decide if the statements are true (t) or false (f).
- •I. Lead-in
- •II. Read the text and find the answers to the questions above. Text a physical chemistry
- •1. Define if the sentences are true (t) or false (f).
- •2. Find in the text English equivalents to the following Russian words and word-combinations.
- •3. Fill in the gaps in the following sentences using the text above. Translate the sentences.
- •4. Find in the text the synonyms for the following words.
- •5. What notions do these groups of key words describe?
- •6. Read the following text about thermodynamics and unscramble the letters in the brackets to find the correct word. Translate the text.
- •7. Noun, verb, adjective, adverb, participle or preposition? What are the underlined words in each sentence?
- •8. Read the following quotations. What do they mean? Discuss them with your groupmates. Express agreement or disagreement.
- •Physical chemistry
- •III. Read the following text. What is the meaning of the words and word-combinations in bold? text b colloids
- •Help the student to solve the problems concerning colloids.
- •2. Find ten words in the wordsearch from the text b. (→, ↓)
- •3. Match the words from the box with the pictures.
- •4. Translate the sentences into English without using a dictionary.
- •5. Look at the picture and comment on it from the point of view of chemistry.
- •6. Read the following words and word-combinations.
- •How does soap work?
- •Active vocabulary unit 1
- •Translation practice text 1 chemistry around us
- •Text 2 enzymes
- •Vitamins
- •Text 4 micelle
- •Text 5 environmental chemistry
- •Text 6 cell phone chemistry
- •Text 7 alcohols
- •Text 8 keto-enol tautomerism
- •Text 9 coordination chemistry
- •Text 10 liquid-liquid extraction
- •Appendices
- •Chemical elements
- •How to read chemical formulas
- •How to read chemical equations
- •Irregular verbs
- •Useful expressions for making a presentation
- •References
Text 10 liquid-liquid extraction
Liquid–liquid extraction (LLE) consists in transferring one (or more) solute(s) contained in a feed solution to another immiscible liquid (solvent). The solvent that is enriched in solute(s) is called extract. The feed solution that is depleted in solute(s) is called raffinate.
Liquid–liquid extraction also known as solvent extraction and partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. It is an extraction of a substance from one liquid into another liquid phase. Liquid–liquid extraction is a basic technique in chemical laboratories, where it is performed using a variety of apparatus, from separatory funnels to countercurrent distribution equipment. This type of process is commonly performed after a chemical reaction as part of the work-up.
The term partitioning is commonly used to refer to the underlying chemical and physical processes involved in liquid–liquid extraction, but on another reading may be fully synonymous with it. The term solvent extraction can also refer to the separation of a substance from a mixture by preferentially dissolving that substance in a suitable solvent. In that case, a soluble compound is separated from an insoluble compound or a complex matrix.
Solvent extraction is used in nuclear reprocessing, ore processing, the production of fine organic compounds, the processing of perfumes, the production of vegetable oils and biodiesel, and other industries.
Liquid–liquid extraction is possible in non-aqueous systems: In a system consisting of a molten metal in contact with molten salts, metals can be extracted from one phase to the other. This is related to a mercury electrode where a metal can be reduced, the metal will often then dissolve in the mercury to form an amalgam that modifies its electrochemistry greatly. For example, it is possible for sodium cations to be reduced at a mercury cathode to form sodium amalgam, while at an inert electrode (such as platinum) the sodium cations are not reduced. Instead, water is reduced to hydrogen. A detergent or fine solid can be used to stabilize an emulsion, or third phase.
Application in analytical chemistry. Often there are chemical species present or necessary at one stage of sample processing that will interfere with the analysis. For example, some air monitoring is performed by drawing air through a small glass tube filled with sorbent particles that have been coated with a chemical to stabilize or derivatize the analyte of interest. The coating may be of such a concentration or characteristics that it would damage the instrumentation or interfere with the analysis. If the sample can be extracted from the sorbent using a nonpolar solvent (such as toluene or carbon disulfide), and the coating is polar (such as HBr or phosphoric acid) the dissolved coating will partition into the aqueous phase. Clearly the reverse is true as well, using polar extraction solvent and a nonpolar solvent to partition a nonpolar interferent. A small aliquat of the organic phase (or in the latter case, (polar phase) can then be injected into the instrument for analysis.