3 Part One. The Predicate

Hydrogen Production
Hydrogen is a very widely distributed clement. 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.

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 (-259°C or 14K) and boiling point (-252.7°C) are very low, only those of helium are lower. Liquid hydrogen, with density 0.070 g/cm^-3 is the tightest of all liquids. Crystalline hydrogen, with density 0.088 g/cm^-3 is also the lightest of all crystalline substances. Hydrogen is very slightly soluble in water, 1 litre of water at 0°C 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 as sulphuric acid, H₂SO₄, with a metal such as zinc. The equation for the reaction is:

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 600°C. The reaction that occurs is

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:

There is, of course, nothing spccial 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 (x=0.9) react with water as vigorously as sodium, and metals with electronegativity about the same as that of iron (x=1.8) react with steam in about the same way as iron.
Mashq 4. Ayting-chi, matnning mazmuni haqidagi taxminlaringiz tasdiqlanganmi? Nimada?

Mashq 5. Matnni tematik bo'limlarga ajrating va har bir qismga sarlavha qo'ying.

Mashq 6. Matn nima haqida gapirish a) vodorodni taqsimlash to'g'risida; b) vodorodning fizik xususiyatlari.

Mashq 7. Matnda sanoatdagi vodorod ishlab chiqarish tavsifini toping va ushbu parchani o’zbek tiliga tarjima qiling.