Compare the meanings of the verb with and without prepositions. Choose one from each line and make up sentences with them.
Come – come back – come off – come out; decide – decide upon; go – go back – go on – go away – go out – go in for; stand – stand up – stand for; make – make up – make out; find – find out; set – set up; give – give away – give back – give off – give up; get – get off – get out – get together – get up; consist in – consist of; use – use up.
Complete the sentences using the appropriate derivatives of the words on the right.
| Although hydrogen is 1) … combustible, yet it is not a 2) … of combustion; that is, substances will not burn in it. At ordinary temperatures hydrogen is not an 3) … element. But under certain 4) … it combines with many elements. For example, if a 5) … of hydrogen and chlorine is exposed to the sunlight, the two gases will combine with 6) … forming hydrogen 7) … . Under right conditions hydrogen combines with nitrogen forming ammonia, and with 8) … forming hydrogen 9) … . If a mixture of hydrogen and oxygen is heated to about 800°C a 10) … explosion occurs and water is formed. | ready |
| support | |
| inactivity | |
| conditional | |
| mix | |
| explode | |
| chlorine | |
| sulphuric | |
| sulphur | |
| violence |
Try to guess the missing words. Some letters are given and the number of letters equals the number of dots.
Hydrogen was discovered by the famous English ph……t Henry Cavendish, and it was a most v……e finding to chemists. Hydrogen helped them to understand the s…….e of acids and b.s.s, these most important classes of chemical c……ds.
It became an important lab…..ry reagent for precipitating metals from s…….s of salts, and for reducing metallic o..d.s. Astrophysicists, who studied the c..p…..on and structure of stars stated that hydrogen is e…..t Number One in the U…..se. It is the main c.m…en. of the Sun and the stars. Another remarkable p…..ty of hydrogen is that its a..m emits rad….ons having a wave-l….h of 21 centimetres. This is called a Universe c.ns…t because it is the same t……out the Universe. So, the scientists organize radio co…n..a…ns with other inh….ed worlds on the hydrogen wave.
Translate the sentences into English. Mind Past Tenses in Active and Passive Voice.
1. Водород был впервые получен в 1776 году. 2. Его получил Генри Кавендиш, который в то время работал в Лондоне. 3. Он получал водород растворением цинка, железа или олова в разбавленной серной или соляной кислоте. 4. Комитет решил установить атомный вес водорода 1.008, а кислорода – 16.000. 5. Водород – самый лёгкий и один из наиболее распространённых элементов на Земле. 6. Название "водород" означает "образующий воду". 7. Учёные знают три изотопных формы водорода: водород (или протий), дейтерий, тритий. 8. Тритий – радиоактивная изотопная форма водорода с коротким периодом полураспада. 9. Гидриды разлагаются в воде, испуская водород. 10. Водород – это важный лабораторный реагент, который помогает осаждать металлы в растворах солей.
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Answer the following questions according to the text.
1. What kind of gas is hydrogen?
2. Why was this gas named "water-former"?
3. Why did chemists choose hydrogen the unit of measurement for the masses of other elements?
4. What are the isotopic forms of hydrogen?
5. What is the structure of a hydrogen ion?
6. Does hydrogen occur free in nature?
7. In what forms does hydrogen mostly occur in nature?
8. How is hydrogen usually obtained?
9. Does hydrogen support combustion?
10. How is hydrogen used in astrophysics?
Section II
TEXT B
Notes on the text:
equation – уравнение; steam – пар; heat – теплота; ignite – воспламенить; filings – металлические опилки, стружка; availability – доступность
Skim the text and entitle it.
Hydrogen is a very widely distributed element. It is found in most of the substances that constitute living matter, and in many inorganic substances. There are more compounds of hydrogen known than of any other element.
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Free hydrogen, H2, is a colourless, odourless, and tasteless gas. It is the lightest of all gases, its density is about one-fourteenth that of air. Its melting point (–259ºC or 14K) and boiling point (–252.7ºC) are very low, only those of helium are lower. Liquid hydrogen, with density 0.07 g/cm3, is the lightest of all liquids. Crystalline hydrogen, with density 0.088 g/cm3, is also the lightest of all crystalline substances. Hydrogen is very slightly soluble in water; 1 litre of water at 0ºC dissolves only 21.5 ml of hydrogen gas under 1-atm pressure. The solubility decreases with increasing temperature, and increases with the increase in the pressure of the gas.
In the laboratory, hydrogen is easily made by the reaction of an acid such a sulphuric acid, H2SO4, with a metal such as zinc. The equation for the reaction is:
H2SO4(aq) + Zn(c) → ZnSO4(aq) + H2(g).
Sometimes hydrogen is prepared by the reaction of some metals with water or steam. Sodium and the other alkali metals react very vigorously with water, so vigorously as to generate enough heat to ignite the liberated hydrogen. An alloy of lead and sodium, which reacts less vigorously, is sometimes used for the preparation of hydrogen.
Much of the hydrogen that is used in industry is produced by the reaction of iron with steam. The steam from a boiler is passed over iron filings heated to a temperature of about 600ºC. The reaction that occurs is:
3Fe(c) + 4H2O(g) → Fe3O4(c) + 4H2(g).
After a mass of iron has been used in this way for some time, it is largely converted into iron oxide, Fe3O4. The iron can then be regenerated by passing carbon monoxide, CO, over the heated oxide:
Fe3O4(c) + 4CO(g) → 3Fe(c) + 4CO2(g).
There is, of course, nothing special about sodium and iron, except their low cost and availability, that is the reason why they are used for the preparation of hydrogen. Other metals with electronegativity about the same as that of sodium (χ=0.9) react with water as vigorously as sodium and metals with electronegativity about the same as that of iron (χ=1.8) react with steam in about the same way as iron.
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