Famous People
Joseph
Louis Gay-Lussac (1778-1850)
Gay Lussac was a French chemist and physicist. He grew up during both the French and Chemical Revolutions. When he was about twenty-four years old, Gay-Lussac formulated the law that a gas expands linearly with a fixed pressure and rising temperature. He did this in 1802, but the discovery later became known as Charles's Law, in honor of Jacques Charles, who had arrived at nearly the same conclusion 15 years earlier but had not published it. Gay Lussac made several daring ascents of over 7,000 meters above sea level in hydrogen-filled balloons. That allowed him to investigate other aspects of gases. He gathered magnetic measurements at various altitudes, took pressure, temperature, and humidity measurements and samples of air, which he later analyzed chemically. Perhaps what he is most well-known for is the Law of Combining Volumes of Gases which states that the volumes of reacting gases and their products at the same temperature and pressure can be expressed as ratios of small whole numbers. E.g. hydrogen combines with oxygen in a 2:1 ratio by volume to produce a volume of water vapor equal to the initial volume of hydrogen or twice the initial volume of oxygen. Gay-Lussac was respected by his colleagues for his careful, elegant, experimental work. He devised many new types of apparatus such as the portable barometer, an improved pipette and burette.
Unit X. The Infinitive Construction Introduced by the Preposition ‘’for’’
Read the following sentences. State the voice and the tense forms of the predicates. Translate the sentences into Russian, paying attention to the infinitive construction.
The temperature was too low for the substance to ignite.
For these experiments to be carried out successfully we shall follow some rules.
A new computer program is needed for these data to be processed as soon as possible.
For this effect to be understood researchers carried out a lot of experiments.
The speed of the particles is too high for us to study in detail.
The time taken for equilibrium conditions to occur is small.
The lithium nucleus is too small for so many collisions to occur.
For a force to exist there must be two objects involved.
Here is one more point for the speaker to explain.
The tendency was for the steam to condense.
For a reaction to take place, an A molecule must first meet a B molecule.
It is possible for the reaction to occur.
The only conclusion for him to make was the following.
The tendency for the substance to become ionized at high temperatures was investigated.
It is not usual for the phosphatic uranium materials to be used as a commercial source for uranium.
Read the following text. Find the predicate in each sentence and state the voice and tense form. Which of the sentences contain the infinitive construction? Translate the text into Russian.
Old and Modern Theories of Heat
Till the eighteenth century, scientists considered heat to be an invisible fluid with special properties called caloric (теплород) (from the Latin word for heat). They believed the caloric to flow from one body to another. According to this theory while a body was heated, the caloric particles were attracted to each individual molecule but repelled each other. The more caloric the molecule had, the more the substance expanded.
The expansion of gases according to this theory was explained in the following way. The theory said that gases expanded much more than solids because each gas molecule was so thickly coated with caloric that the caloric repelling force between molecules was greater than any attracting force.
The caloric theory seemed to have explained a lot of things about heat. But experiments found more and more points for which the caloric theory could not provide explanation. For them to be explained a new theory was needed.
In 1738, Swiss scientist Daniel Bernoulli published Hydrodynamica which laid the basis for the kinetic theory of gases. In this work, Bernoulli positioned the argument, still used to this day, that gases consist of great numbers of molecules moving in all directions, that their impact on a surface causes the gas pressure that we feel, and heat is simply the kinetic energy of their motion. The faster the molecule move, the higher is the temperature of the molecule. In other words, the temperature of a body increases when kinetic energy increases. The new theory was given the name of kinetic theory (from the Greek word kino which means 'movement'). Later the kinetic theory was developed by such scientists as Count Rumford, James Clark Maxwell, and others.
According to the molecular-kinetic theory, the molecules of a solid body are always in a state of slight vibration about their fixed positions. The higher the temperature of a body, the more widely all the molecules vibrate, each of the molecules moving slightly apart from the others. The lower the temperature of a body, the less widely its molecules vibrate, moving closer to each other. Due to such changes, bodies either expand or contract.
Transcribe the following words, practice reading them, give Russian equivalents:
Theory, century, scientist, invisible, substance, tiny, surround, expand, expansion, experiment, provide, explanation, elaboration, vibrate, collide
Are the following sentences true or false? Correct the false sentences
1. According to the kinetic theory heat was considered to be an invisible fluid with
special properties.
2. Scientists believed caloric to repel the molecules of a substance.
3. Caloric theory explained all the things about heat.
4. The molecules of a solid body do not move.
5. Bodies can either expand or contract because of temperature changes.
6. According to the kinetic theory, heat is considered to be a form of energy.
Answer the questions.
1. What theory of heat existed until the 18-th century?
2. What did the scientists of the past call ‘caloric’?
3. How did the caloric theory explain the expansion of substances with heat?
4. Why was a new theory of heat needed?
5. What is heat according to the new theory?
6. What does the temperature of the molecule depend on according to the new theory of
heat?
7. Why was the new theory named ‘kinetic theory’?
8. Do the molecules of a solid body remain motionless?
9. Why do bodies expand or contract according to the kinetic theory?