2. UNIT 4 Defining & Explaining Vocabulary Revision of the vocabulary WORD FORMATION (U2 -> p28): N from Vbs Grammar and functions Revision of grammar structures Expanding definitions & Giving explanations Relative clauses Shortened Relative Clauses WHAT vs WHICH Uses of THAT

3. TRANSLATION: METALS (p 47) Why DO ENGINEERS USE (1) SO MANY METALS (2) today when THERE ARE (3) other materials, especially plastics, which are available? A material is generally used because IT OFFERS (4) the required STRENGTH (5) and other properties at minimum cost. Appearance is also an important factor. The main advantage of metals is THEIR STRENGTH AND TOUGHNESS (6). CONCRETE (7) may be cheaper and (IT) IS OFTEN/FREQUENTLY/WIDELY/COMMONLY USED (8) in building, but even concrete DEPENDS ON (9) its core of steel for strength.

4. TRANSLATION: METALS (p 47) Plastics are LIGHTER AND MORE CORROSION RESISTANT/MORE RESISTANT TO CCORRORION (10) but they are not usually as strong. Another problem with plastics is WHAT (WE HAVE) TO DO with them after use (11). Metal objects CAN BE BROKEN down (12) and the metals recycled; plastics can only be dumped or burned. Not all metals are strong, however. Copper and aluminium are both fairly WEAK (13), but if THEY ARE MIXED together (14), the result is AN ALLOY (15) called aluminium bronze, WHICH IS MUCH STRONGER (16) than either pure copper or pure aluminium. Alloying is an important method of OBTAINING (17) whatever special properties are required: strength, toughness, resistance to wear, magnetic properties, high electrical resistance or corrosion resistance.

5. TRANSLATION: METALS (p 48) The properties of a metal can be further improved by use of heat treatment. Heat treatment is the term given to A NUMBER/VARIETY OF DIFFERENT procedures(18) IN WHICH (19) the properties of metals and alloys are changed. It usually CONSISTS OF HEATING (20) the metal or alloy to a selected temperature BELOW ITS MELTING POINT (21) and then COOLING IT (DOWN) (22) at a certain rate to obtain those properties which are required. For example, hardening is used to make metals harder. Tempering MAKES THEM SOFTER AND LESS BRITTLE (23). Annealing is carried out to make a metal soft so that it can be machined MORE EASILY (24) IN THIS WAY (25), metallic materials can be produced to meet every kind of engineering specification and requirement. Methods of extracting, producing and treating metals ARE BEING DEVELOPED (26) all the time to meet engineering requirements. This means that there is an enormous variety of metals and metallic materials FROM WHICH TO CHOOSE (27).

6. EXERCISE (prep) p 49 1.The nucleus is the part of the atom around which smaller particles rotate. 2.The magnitude of a force is equal to the number of grams constituting the mass on which it acts multiplied by the number of cm/sc. 3.Polymers are the elements on which plastics are based 4.Dynamics is a discipline in which movement is studied in detail. 5.A thermostat is a device with which temperature can be controlled. 6.Our engineers are designing a technique by which energy loss can be significantly decreased. 7.There are many ways in which the properties of steel can be improved. 8.Conductors are materials through which electricity can flow 9.A container of hot water gives off heat to the objects by which it is surrounded 10.The melting point is the temperature at which metals change from solid to liquid

7. Exercise B p 50 1.Strength is the main property that steel offers. 2.The process which/that is known as polymerization consists of joining different polymers of/from which plastics are made. 3.Electrons, the electrical charge of which is negative, are the responsible particles for the production of electricity. 4.The high speeds at which the rotor in a generator turns produce large amounts of electricity. 5.An electrolytic cell is the place where/in which the electrolytic process takes place. 6.The discovery of semiconductors allowed the mass production of chips, which reduced the cost of computers significantly. 7.Lead whose symbol is Pb, is the heaviest metal. 8.There are many different ways in which we may change the properties of materials.

8. Exercise B (shortened R.C.) p 50 1.Alloys are materials CONTAINING (that contain) at least one metal 2.The cables SUPPLYING (that supplied) the electricity were damaged in the storm 3.This report contains the results OBTAINED (that were obtained) from the test. 4.The temperatures SHOWN (that are shown) in the graph are given in degrees centigrade. 5.The coolant NOT FLOWING (that does not flow) through the radiator may cause overheating. 6.The mixture FED (that is fed) to the machine is then processed. 7.We analyzed the samples TAKEN (that were taken) from polluted water. 8.A new synthetic material DEVELOPED (that was developed) last year is already …. 9.The metal SURROUNDING (that surrounds) the engine must resist high temperatures 10.The metals KNOWN (that are known) as ferrous metals contain iron

9. WHAT vs WHICH p 51 1.The mixture of copper and tin is WHAT is known as bronze, WHICH was probably the first alloy used by man. 2.We need to benefit from solar energy, WHICH is difficult in some countries. 3.They were not surprised at WHAT this device can detect, because they knew WHAT to expect. 4.The maintenance engineers did WHAT they could, WHICH wasn't much. 5.Many companies don’t know WHAT to do with their waste, WHICH makes for serious environmental problems. 6.He is familiar with several programming languages, WHICH makes him suitable for the job. 7.We don’t know WHAT caused the accident in the power plant. 8.WHAT goes up must come down. 9.It doesn’t matter WHAT you do, the system won’t work properly anyway. 10.I am sure that WHAT the technicians say is correct, but we should look for better alternatives to provide clean energy.

10. LISTENING: Alloys (p 52) (00:55’) The properties of an alloy DEPEND ON THE PROPERTIES OF THE ELEMENTS THAT IT CONTAINS although the alloy behaves IN A DIFFERENT WAY For example, there is an alloy of IRON THAT IS EVEN MORE MAGNETIC THAN PURE IRON The usual method OF MAKING AN ALLOY is to heat the different elements UNTIL THEY MELT then to mix them Thus, an alloy is a solution RATHER THAN A SIMPLE MIXTURE As you know, the properties of a solution are not simply A MIXTURE OF THE PROPERTIES OF ITS COMPONENTS Water for example FREEZES AT 0ºC and sodium chloride MELTS AT 801ºC, but if sodium chloride is dissolved in water to form a strong solution of saltTHIS SOLUTION FREEZES AT –23ºC. In fact, as a general rule, A SOLUTION FREEZES AT A LOWER TEMPERATURE THAN ITS COMPONENTS DO And since alloys are SOLID SOLUTIONS it should not surprise you to learn thatTHEY BEHAVE IN A SIMILAR WAY an alloy usually has A LOWER MELTING POINT than the substances OF WHICH IT IS COMPOSED. For example, PURE IRON MELTS AT 1,500ºC and carbon at 3,350ºC, but cast iron, AN ALLOY OF IRON & CARBON, melts at 1,150ºC.

11. CORRECT MISTAKES p 53 1.The properties of an alloy depend on the materials that IT contains. 2.Electrons orbiting farther from the nucleus are easily drawn away. 3.An electrolytic cell is the place in which ELECTROLYSIS takes place. 4.Steel is an alloy WHOSE composition consists of carbon and iron. 5.Go on with what you were doing. 6.An alloy is the name GIVEN to the material that (0) is formed by a metal and another element. 7.Conductors are materials THROUGH WHICH electricity can flow 8.The mixture of copper and zinc is called brass, WHICH (0) is the most common non-ferrous alloy. 9.The properties of alloys are better than THOSE observed in pure metals 10.Metals can be heated to a certain temperature above (0) which their properties change. 11.The temperature AT WHICH iron melts is 1,550ºC.

12. USES of THAT p 52 Relative pronoun (THAT or WHICH) : e.g. The materials THAT /WHICH are used in structures must be very strong Conjunction: THAT (after vbs such as TO SAY, TO STATE, TO KNOW THAT…). E.g. She said THAT it was raining Adj + N /Pronoun: THIS/THESE (+ N) THAT / THOSE (+ N) e.g. Iron is commonly used in engineering. This/That (material) is alloyed with other metals e.g. Zinc and nickel are very strong. These/Those (materials) are commonly used in alloys

13. USES of THAT p 52 Pronoun: - El/Los (pronoun) + ADJECTIVE =the one / the ones. E.g. In eletrolysis the more active electrode releases ions that are attracted by the LESS ACTIVE ONE (electrode ) -El/Los (pronoun) + OF/ Short Rel Clause (typically used with comparison) (el de/ el que) = THAT/THOSE OF/short REL CL –The density of iron is higher than THAT OF zinc: la densidad del hierro es mayor que la (densidad) del cinc –The results are better than THOSE (which were) presented last year: los resultados son mejores los (resultados) que se presentaron el año pasado

14. EXERCISE: Uses of THAT p 53 1.The microscope showed that (Conj) the membrane of TiNi was thicker than that of (Pron) stainless steel 2.The result is a plethora of choices that (Relat) enable today’s engineers to fine- tune the selection process 3.Natural materials such as obsidian and tektites have compositions and properties similar to those (Pron) of synthetic glass. 4.Plastics have a lower melting point than that (Pron) of metals 5.The results obtained in the experiment are compared to those (Pron) given in the specifications 6.The toughness and hardness of a steel that (Relat) is not heat treated depend on the amount of carbon that (Relat) is added to the mixture 7.The results that (Relat) were obtained during the experiment show clearly that (Conj) the elasticity of steel is higher than that (Pron) found in pure iron. 8.This alloy has a high tensile strength, comparable to that (Pron) of the duplex stainless steels Engineers must choose the materials that (Relat) they consider best suited for a particular purpose 9.Wilm discovered that (Conj) the alloy increased in hardness when left to age at room temperature 10.Polymers can never have a degree of order equivalent to that (Pron) of low molecular materials like ice or common salt

15. Unit 4: USES OF THAT Pronoun 1.Steel has a density about eight times that of water (LA DEL AGUA) 2.Amorphous thermoplastics do not have a fixed melting temperature like that of (COMO LA DE) the semi-crystalline thermoplastics. 3.Common glass like that (which is) used (COMO EL QUE SE USA) for windows, contains metal oxides 4.We have seen that (QUE) ferrous metals are those which have iron (LOS QUE TIENEN HIERRO) as their main constituent 5.The tensile strength of aluminium is higher than that of iron (MAYOR QUE LA DEL HIERRO) 6.The code indicates that (QUE) the properties that / which (QUE) are obtained after heat treatment are different from those (which are) obtained (DE LAS QUE SE OBTIENEN) before heating the metal

16. Unit 4: USES OF THAT Pronoun 7.The data in the table show that (QUE) the bioethanol thermal characteristics are comparable to those (which are) found (A LAS QUE SE ENCUENTRAN = find) in sugar and lignocellulosic materials, indicating that it is (QUE ES) technically viable to produce bioethanol from biomass 8.The contributions from bioproducts, especially those that/ which have (LOS QUE TIENEN) a higher economic value, such as bio- butanol, should not be totally ignored. 9.The estimated price for biodiesel produced from soybean oil and waste frying oil is $1.35/L, which (QUE) is similar to that of (AL DEL) petro-diesel 10.The results (that/which are) obtained (QUE SE OBTIENEN) after the experiment are compared to/with those (that/which are) shown (CON LOS QUE SE MUESTRAN = show) in the specifications

17. WORD FORMATION (U2 p 28) NOUN from VERB -ing -> English (e.g. building) -tion/sion ->Latin (e.g. Explanation/emission) - ment (e.g. management) -er/or (object) (e.g. boiler/conductor) -ure (e.g. mixture) -ent/ant (e.g. content/coolant) -nce (e.g. performance) -age (e.g. drainage) -al (e.g. disposal) -y (e.g. discovery)

18. WORD FORMATION: p 28 1.EXPOSURE to GASEOUS fluorine. 2.IMPROVEMENTS … RESISTANCE …FULLY … PITTING 3.DENSITY … its SUBSTITUTION …. WEIGHT …HARMFUL … EMISSIONS 4.its STRENGTH … its ABILITY … DEFORMATION …its RESISTANCE … to DEFLECTION 5.COMPONENTS … CHEMICALLY …. ENVIRONMENTALLY safer COOLANTS … higher PRESSURES

19. WORD FORMATION: Aluminium p 29 ACTIVITY ENGINEERING DEVELOPMENT APPLICATIONS TOUGHNESS or DUCTILITY FAILURE. ACCEPTANCE COMPONENTS REFRIGERANTS or COOLANTS and PRESSURES WORKABILITY and corrosion RESISTANCE ABILITY STRENGTH TREATMENT