Nevertheless — тем не менее
Just as — также как
To result from — происходить, проистекать text. Chemical and physical changes
An iron rod held in the fire long enough increases in energy content until it becomes too hot to hold in the unprotected hand. Nevertheless the rod is still iron, and when cooled to its original temperature, its properties are just as they were before.
The heating and the subsequent cooling of the rod are examples of physical changes.
A physical change may result in a more or less temporary alteration of a few of the properties of a substance involved, but no change of composition results from it and most of the altered properties usually regain their former value.
Changes of this type are numerous and many of them are familiar to everyone. As an example we may take the behaviour of ice when it is heated.
At first when heated the ice melts, when further heated, the liquid water boils forming the gaseous water (or the steam, as it is usually called). If the steam is cooled, the process is re
versed—when cooled sufficiently, the ice results. The substance present in every instance was water. This experiment shows that there are three physical states in which the substance may exist.
If the rod concerned is placed in a container of hydrochloric acid, it will be noted that bubbles begin to form on the rod. If the rod involved is left in the acid for some time, the evolution of gas will continue. When examined, it will be found that the rod has diminished in mass or disappeared altogether. The liquid in the container if examined will have a greenish colour.
If evaporated, a mass of greenish crystals will be obtained. The crystals will have totally different properties. This is an example of a chemical change. So, a chemical change may be called a chemical reaction or simply a reaction, the substances entering into a chemical reaction are called reactants.
Phenomena accompanied by radical changes of substances are called chemical phenomena.
Remember
enough familiar
increase behaviour
content to melt
until further
sufficiently
instance state to note bubble
nevertheless
to cool original subsequent to result in
to
result from
temporary
alteration
composition
to
regain
value
evolution
to
diminish to disappear altogether totally simply
Ex. 9. Answer the following questions:
1. When does an iron rod increase in energy content? 2. What happens when an iron rod cools to its original temperature? 3. What are the examples of a physical change? 4. What kind of changes are familiar to everyone? 5. What happens to the ice when it is heated? 6. When do bubbles begin to form on the rod? 7. When does the rod disappear altogether? 8. What is a chemical change? 9. What does this lesson deal with?
Ex. 10. Find in the text the words with the suffix “-ed” and state their functions.
Ex. 11. Translate the following sentences into Russian, mind the Participles:
change accompanied by the evolution of heat is described as exothermic, while one in which heat is absorbed is called endothermic. 2. The substance begins to melt if heated to a sufficient temperature. 3. The method involved depended on a number of factors described earlier. 4. If a given amount of energy is put into a machine, the very amount will be developed, neither more nor less. 5. Experiments made with various elastic materials have shown that there is a simple relationship between the acting force and the resistance force. 6. A given molecule is able to move within the liquid from place to place. 7. Solids can be changed to gases when they are heated.
The experiments carried out in our laboratory resulted in many new investigations in the field of ceramics. 9. The energy produced by the splitting of the nucleus of an atom is called “nuclear” or atomic energy. 10. Mostly atoms contain uncharged particles called neutrons.
Ex. 12. Open the brackets translating the Russian words into English:
1. An iron rod (нагретый) in the fire increases in energy content. 2. (При охлаждении) to the original temperature the substance becomes solid. 3. The question (рассмотренный, о котором шла речь) was discussed at the last meeting. 4. The new experiment (о котором говорили) so much will be carried out again very soon. 5. The piece of ice (помещенный) in the water began to melt. 6. (При нагревании) ice melts. 7. The text (переписанный) by him was very useful in our work. 8. The new device (показанный) by our professor was very interesting. 9. (При выпаривании) a mass of greenish crystals will be obtained. 10. The work (выполненная) in time was very important.
Ex. 13. Find the pairs of synonyms and remember them:
to rise, to change, to occur, to alter, to get, to take place, to obtain, to increase.
Ex. 14. Find the pairs of antonyms and remember them:
to enter, to appear, to leave, to disappear, to evolve, to involve, to cool, to continue, to heat, to cease.
Ex. 15. Choose the Russian equivalents from the right column:
помещать
например
вначале
приводить
first
of all to replace to place
for example more or less at first to result in
замещать более менее прежде всего
heat energy may be employed to produce steam. 2. iquid is heated the molecules move faster. 3. Heat uses an increase in kinetic energy. 4. Heat may also change of state without any change of temperature, isov stated that heat phenomena were due to the molecules. 6. If you want to heat this mixture, put ; container. 7. The lecture will take place in our
They placed new devices on the laboratory ). When the students finish their work in the la- they must put everything back in place.
ns!ate the text using a dictionary:
oins have lain in sea water for hundreds of years lrnishing, but most substances change with time, snow melts to water, copper roofs go green with age i. Scientists have studied these and many other id found that some are brought about by changes in :e alone.
id ice melts. Further heating raises the temperature ;er until it boils and turns to steam, cooled the steam turns back to water and the water ther cooled until it changes to ice. ompare this kind of change with the rusting of iron that iron cannot be easily “unrusted”. This is be- is a different substance from the iron and has properties.
aging from iron to rust the iron has undergone a change or a chemical reaction.
nslate the following text and render it:
nakes a chemical reaction go? This is a question that nd students have asked since they began to examine reactions.
beginning of the nineteenth century the question was saying that two substances react if they have a affinity” for each other. The answer involved had no ; until some quantitative meaning was given to affinity”, and some way was found to measure or
be thought that the heat of a reaction is its driving the reaction will proceed if it evolves heat, and not it absorbs heat. This idea, however, is wrong as many :an proceed even though they absorb heat.
LESSON 13
Grammar: 1. The Perfect Participle.