What are the properties of oxygen? Weight of 1 m3 of oxygen. Weight of liquid oxygen. Methods for obtaining oxygen.

How much does air weigh?

Like all objects around us, air is also subject to gravity. It is this that gives the air a weight that is equal to 1 kg per 1 cm². The density of air is about 1.2 kg/m³, that is, a cube with a side of 1 m filled with air weighs 1.2 kg.”

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What are the properties of oxygen? Weight of 1 m3 of oxygen. Weight of liquid oxygen. Methods for obtaining oxygen.

At normal pressure and normal temperature, oxygen is a transparent gas without color, smell or taste. It does not burn, but actively supports combustion.

Weight of 1 m3 of oxygen.

At 0° G and pressure 760 mmHg. 1 m3 of oxygen weighs 1.43 kg. When cooled to a temperature of -186° and normal atmospheric pressure, oxygen turns into a transparent, easily evaporating bluish liquid.

Weight of liquid oxygen.

One liter of liquid oxygen weighs 1.13 kg and, when evaporated, produces about 800 liters of gas.

Oxygen energetically combines with almost all elements, with the exception of noble metals (gold, silver, platinum, etc.), rare gases (helium, argon, neon, etc.) and fluorine.

When compressed oxygen (over 30 kg/cm2) comes into contact with oils and fats, it instantly oxidizes them, releasing a large amount of heat, which contributes to the ignition of the oil or fat and can lead to an explosion.

Metals combine especially actively with oxygen. The oxygen cutting process is based on their ability to burn in a stream of pure oxygen.

Also read: Oxygen cylinder design. Valve for oxygen cylinder. Safety precautions when working with an oxygen cylinder.

Methods for obtaining oxygen.

There are several ways to obtain oxygen. The most common and cheapest way to obtain oxygen from atmospheric air is by deep cooling. Atmospheric air serves as the main source of technical oxygen.

Air contains 78% nitrogen, 21% oxygen and 1% argon and other impurities.

According to GOST 5583-58 , gaseous technical oxygen used for gas-flame processing of metals and for medical purposes must have a purity of: 99.5% (highest grade), 99.2% (1st grade) and 98.5% (2nd grade). th variety). The impurity in the amount of 0.5-1.5% mainly consists of nitrogen and argon.

To obtain oxygen, there are special installations in which purified and dried air is converted into liquid by compression and cooling.

Liquid air is separated into oxygen and nitrogen. The separation method is based on the fact that liquid nitrogen and oxygen boil and evaporate at different temperatures: nitrogen at a temperature of -196°C, and oxygen at a temperature of -183°C. When air turns into liquid and then evaporates, nitrogen, which has a lower boiling point than oxygen, begins to evaporate first.

Oxygen cutting uses oxygen gas. Therefore, liquid oxygen with the help of special devices - gasifiers - is converted into a gaseous state and in this form is supplied to the place of consumption through a gas pipeline or in special cylinders.

Oxygen can be supplied to consumers in liquid form. Transporting liquid oxygen is much cheaper and safer than gaseous oxygen. Liquid oxygen is stored and transported in special vessels - tanks.

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Application

Technical Oxygen is used as an oxidizing agent in metallurgy (see, for example, Oxygen-converter process), in gas-flame processing of metals (see, for example, Oxygen cutting), in chemical. industry when receiving arts. liquid fuel, lubricating oils, nitric and sulfuric acids, methanol, ammonia and ammonia fertilizers, metal peroxides, etc. Pure K. is used in oxygen-breathing apparatus in space. ships, submarines, when climbing to high altitudes, carrying out underwater work, for medicinal purposes in medicine (see article Oxygen therapy). Liquid carbon is used as an oxidizer for rocket fuels and during blasting operations. Aqueous emulsions of solutions of gaseous K. in some organofluorine. solvents are proposed to be used as arts. blood substitutes (eg, perftoran).

Receipt

In prom. On a large scale, water is produced by liquefying and fractional distillation of air (see Art. Air separation), as well as by electrolysis of water. In laboratory conditions, K. is obtained by decomposition when heating hydrogen peroxide (2H2O2 = 2H2O+ O2), metal oxides (for example, mercury oxide: 2HgO = 2Hg + O2), salts of oxygen-containing oxidizing acids (for example, potassium chlorate: 2KClO3 = 2KCl +3O2, potassium permanganate: 2KMnO4=K2MnO4+MnO2+O2), by electrolysis of an aqueous solution of NaOH. Gaseous K. is stored and transported in steel cylinders, painted blue, at a pressure of 15 and 42 MPa, liquid K. - in metallic ones. Dewar vessels or special tank tanks.

Carbon dioxide cylinders 5l 10l 20l 40l 50l GOST 949-73

Carbon dioxide cylinders, small and medium volume, made of carbon and alloy steel GOST 949-73. (CO2 cylinder)

The body of the carbon dioxide cylinder is painted with black enamel, the inscription “ CARBON ACID ” is yellow. The weight of carbon dioxide cylinders is indicated without valves, caps, rings and shoes. Approximate weight: metal cap - 1.8 kg; rings - 0.3 kg; shoe - 5.2 kg

Small volume cylinders can be supplied with a flat bottom. Do you want to buy carbon dioxide cylinders?

We will do the rest ourselves. We will deliver to a transport company or bring you to your city.

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Example: Calculate the volume for 1 kg of oxygen, for 160 g of oxygen, for 8 g of oxygen:

Calculate the volume for 1 kg of oxygen under normal conditions.

V = m · Vm / M = 1,000 grams · 22.4 l/mol / 32 g/mol = 700 liters.

Calculate the volume for 1 kg of oxygen at 30 degrees Celsius (303.15 K), pressure 30 kPa.

V = m R T / p M = 1,000 grams 8.314 J/(mol⋅K) 303.15 K / ( 30 kPa 32 g/mol ) = 2,625.405 liters or 2.625405 m3.

Calculate the volume for 160 g of oxygen under standard conditions.

V = m · Vm / M = 160 grams · 22.4 l/mol / 32 g/mol = 112 liters.

Calculate the volume for 160 g of oxygen at 30 degrees Celsius (303.15 K), pressure 30 kPa.

V = m R T / p M = 160 grams 8.314 J/(mol⋅K) 303.15 K / ( 30 kPa 32 g/mol ) = 420.064 liters.

Calculate the volume for 8 g of oxygen under standard conditions.

V = m · Vm / M = 8 grams · 22.4 l/mol / 32 g/mol = 5.6 liters.

Calculate the volume for 8 g of oxygen at 30 degrees Celsius (303.15 K), pressure 30 kPa.

V = m R T / p M = 8 grams 8.314 J/(mol⋅K) 303.15 K / ( 30 kPa 32 g/mol ) = 21.003 liters.

Properties

The structure of the outer electron shell of the K atom 2s22p4; in compounds exhibits oxidation states –2, –1, rarely +1, +2; Pauling electronegativity 3.44 (the most electronegative element after fluorine); atomic radius 60 pm; the radius of the O2 ion is 121 pm (coordination number 2). In gaseous, liquid, and solid states, oxygen exists in the form of diatomic O2 molecules. O2 molecules are paramagnetic. There is also an allotropic modification of ozone, ozone, consisting of triatomic O3 molecules.

In the main In this state, a carbon atom has an even number of valence electrons, two of which are unpaired. Therefore, K., which does not have a low-energy vacant d-orbital, is in most chem. bivalent compounds. Depending on the nature of the chemical. connections and crystalline type. coordination connection structures K number can be different: 0 (atomic K), 1 (for example, O2, CO2), 2 (for example, H2O, H2O2), 3 (for example, H3O+), 4 (for example, Be oxoacetates and Zn), 6 (e.g. MgO, CdO), 8 (e.g. Na2O, Cs2O). Due to the small radius of the atom, carbon is capable of forming strong π-bonds with other atoms, for example. with K atoms (O2, O3), carbon, nitrogen, sulfur, phosphorus. Therefore, for K. one double bond (494 kJ/mol) is energetically more favorable than two single bonds (146 kJ/mol).

The paramagnetism of O2 molecules is explained by the presence of two unpaired electrons with parallel spins in doubly degenerate antibonding π* orbitals. Since the bonding orbitals of the molecule contain four more electrons than the antibonding orbitals, the bond order in O2 is 2, i.e., the bond between the atoms of carbon is double. If with photochemical or chemical When two electrons with opposite spins appear in one π* orbital, the first excited state appears, the energy of which is 92 kJ/mol higher than the ground one. If, when an atom is excited, two electrons occupy two different π* orbitals and have opposite spins, a second excited state arises, the energy of which is 155 kJ/mol higher than the ground state. Excitation is accompanied by an increase in O–O interatomic distances: from 120.74 pm in the base. state up to 121.55 pm for the first and up to 122.77 pm for the second excited state, which, in turn, leads to a weakening of the O–O bond and an increase in chemical. activity of K. Both excited states of the O2 molecule play an important role in oxidation reactions in the gas phase.

K. is a colorless, odorless, and tasteless gas; tmelt –218.3 °C, tboil –182.9 °C, density of gaseous K. 1428.97 kg/dm3 (at 0 °C and normal pressure). Liquid K. is a pale blue liquid, solid K. is a blue crystalline liquid. substance. At 0 °C, thermal conductivity is 24.65·10-3 W/(m·K), molar heat capacity at constant pressure is 29.27 J/(mol·K), dielectric. permeability of gaseous K. 1.000547, liquid 1.491. K. is poorly soluble in water (3.1% K. by volume at 20 °C), soluble in some organofluorine compounds. solvents, e.g. perfluorodecalin (4500% K. by volume at 0 °C). Means. the amount of K. is dissolved by noble metals: silver, gold and platinum. The solubility of gas in molten silver (2200% by volume at 962 °C) decreases sharply with decreasing temperature, therefore, when cooled in air, the silver melt “boils” and splashes due to the intense release of dissolved oxygen.

K. has a high reactivity, a strong oxidizing agent: it interacts with most simple substances under normal conditions, mainly. with the formation of the corresponding oxides (many reactions that occur slowly at room and lower temperatures, when heated, are accompanied by an explosion and the release of a large amount of heat). K. reacts under normal conditions with hydrogen (water H2O is formed; mixtures of K. with hydrogen are explosive - see Explosive gas), when heated - with sulfur (sulfur dioxide SO2 and sulfur trioxide SO3), carbon (carbon oxide CO, carbon dioxide CO2 ), phosphorus (phosphorus oxides), pl. metals (metal oxides), especially easily with alkali and alkaline earth (mainly metal peroxides and superoxides, e.g. barium peroxide BaO2, potassium superoxide KO2). K interacts with nitrogen at temperatures above 1200 °C or when exposed to electricity. discharge (nitrogen monoxide NO is formed). Compounds of chlorine with xenon, krypton, halogens, gold, and platinum are obtained indirectly. K. does not form chemical. compounds with helium, neon and argon. Liquid K. is also a strong oxidizing agent: cotton wool soaked in it burns instantly when ignited; some volatile organic compounds. substances are capable of spontaneous combustion when they are located at a distance of several meters from an open container of liquid oxygen.

K. forms three ionic forms, each of which determines the properties of the component. chemical class compounds: $\ce{O2^-}$– superoxides (formal oxidation state of the K atom –0.5), $\ce{O2^2^-}$ – peroxide compounds (oxidation state of the K atom –1, for example . hydrogen peroxide H2O2), O2– – oxides (oxidation state of the K atom –2). Positive oxidation states +1 and +2 K are exhibited in fluorides O2F2 and ОF2, respectively. K fluorides are unstable and are strong oxidizing agents and fluorinating reagents.

Molecular K. is a weak ligand and attaches to some complexes of Fe, Co, Mn, and Cu. Among such complexes, the most important is iron porphyrin, which is part of hemoglobin, a protein that transports oxygen in the body of warm-blooded animals.