Physical and chemical properties of hydrogen, physical properties of hydrogen

Physical. Normally, it is colorless and odorless, and the gas density is less than air, making it one of the least dense gases. Insoluble in water.

Chemical properties. 1.Flammability. It can react with oxygen under ignition conditions to produce water. Because the combustion product is only water, it is called the cleanest fuel. Because it is flammable, it is easy to occur when ignited, so its purity should be checked before ignition.

2.Reductiveness. Some oxides can be reduced under heating conditions, such as copper oxide can be reduced when heated.

Physical. Hydrogen is a colorless gas and less dense than air (among all gases, hydrogen has the least density. Under standard conditions, the mass of 1 liter of hydrogen is grams, which is much lighter than air for the same volume).

Because hydrogen is poorly soluble in water, it can be collected using the drain gas collection method. In addition, at a standard atmospheric pressure, at temperature, hydrogen can be converted into a colorless liquid; , it becomes a snow-like solid. At room temperature, hydrogen is very stable and does not easily react with other substances.

But when the conditions change (e.g., ignition, heating, use of catalysts, etc.), the situation is different. For example, hydrogen has strong activity after being adsorbed by metals such as palladium or platinum (especially adsorbed by palladium). Palladium metal has the strongest adsorption effect on hydrogen.

When the volume fraction in the air is 4%-75%, it can cause ** when it encounters an ignition source.

Hydrogen atomic structure.

Hydrogen is a colorless and odorless gas with a density of grams (the lightest gas) under standard conditions, and is poorly soluble in water. At -252, it becomes a colorless liquid, and at -259, it becomes a snowflake-like solid.

Boiling point. k) melting point.

Density. Gas-liquid volume ratio.

974 l/l（15℃，100kpa）

Relative molecular weight.

Critical density. kg/m3

Production method. Water electrolysis, pyrolysis, coal-to-gas, etc.

Critical pressure. Heat of vaporization: 305 kJ kg (h, gas density: kg m3 (1 atm, 0).

Specific volume: m3 kg (1 atm, thermal conductivity: w (m·k) (gas, 1 atm w (m·k) (liquid,

Specific heat capacity: cp = kj (kg·k), cv = kj (kg·k) (1 atm, 25, gas).

Vapor pressure: kpa (normal state, kpa (normal state, kpa) (normal state, k).

Viscosity: mpa·s (gas, normal state).

mpa·s (liquid, equilibrium,

Heavy hydrogen is a colorless, odorless, non-toxic and flammable gas at room temperature and pressure, and is a stable isotope of ordinary hydrogen. It is contained in the hydrogen of the usual water. Its chemical properties are exactly the same as those of ordinary hydrogen. But the mass is larger, and the reaction speed is smaller.

Chemical properties. Hydrogen is stable at room temperature, and can react with many substances under the condition of ignition or heating.

Flammability (can be burned in oxygen or chlorine):

Chemical reaction) ignition of impure hydrogen to occur**, must be pure before ignition of hydrogen, similarly, deuterium (heavy hydrogen) ignition in oxygen can produce heavy water (D2O)).

In this reaction, the combustion flame is pale and under light conditions**.

H2+F2=2HF (Hydrogen and fluorine are mixed to form hydrogen fluoride gas immediately, even under dark conditions).

Reducibility (e.g. reducing certain metal oxides).

h2+cuo

Cu + H2O (displacement reaction).

displacement reaction) 3h2+wo3

W+3H2O (displacement reaction).

Hydrogen can also undergo addition reactions with double or triple bonds.

Physical properties of hydrogen: Under normal circumstances, hydrogen is a colorless and odorless gas; The density is the smallest gas; Insoluble in water, etc. Chemical properties of hydrogen:

1.flammability (uses: high-energy fuels, hydroxide flame welding, metal cutting); 2.

Reducibility (smelting metals). At room temperature and pressure, hydrogen is a highly flammable, colorless, transparent, odorless and tasteless gas that is insoluble in water. Hydrogen is the least dense gas known in the world, the density of hydrogen is only 1 14 of air, that is, hydrogen at 1 standard atmosphere and 0, the density of hydrogen is.

Therefore, hydrogen can be used as a filling gas for airships and hydrogen balloons (because hydrogen is flammable and not safe, airships are now mostly filled with helium). Hydrogen is the substance with the smallest relative molecular mass and is mainly used as a reducing agent. Hydrogen (H2) was first artificially produced in the early 16th century by placing the metal in a strong acid.

1766 In 1781, Henri Cavendish discovered the element hydrogen, which was burned to produce water (2H + O ignition = 2h O), and Lavoisier named the element "hydrogenium" (meaning "substance that produces water", "hydro" is "water", "gen" is "generated", and "ium" is the universal suffix of the element). In the 50s of the 19th century, when the British physician Hexin wrote the New Naturalist Edition (1855), he translated "hydrogen" as "light gas", which means the lightest gas. Industrially, hydrogen is generally produced from natural gas or water gas, rather than using the energy-intensive method of electrolysis of water.

The hydrogen produced is used in large quantities for cracking reactions and ammonia production in the petrochemical industry. Hydrogen molecules can enter the crystal lattice of many metals, causing a phenomenon called "hydrogen embrittlement", making the use of special materials (such as Monel alloy) for hydrogen storage tanks and pipes more complex to design.

Physical properties: the least dense gas, colorless and odorless, insoluble in water.

Chemical properties: flammable, reducible.

Hydrogen is insoluble in water, lighter than air, colorless, and odorless. It is flammable and explosive in the air.

Hydrogen is a colorless and odorless gas, the lightest gas, and it is also a flammable and easy-to-use gas, which is often used as a reducing agent.

1. Hydrogen is a colorless gas with a smaller density than air (under standard conditions, the mass of 1 liter of hydrogen is grams, and the same volume is much lighter than air).

2. Hydrogen is insoluble in water.

3. At a standard atmospheric pressure, hydrogen can be converted into a colorless liquid at a temperature; , it becomes a snow-like solid.

Hydrogen is a colorless and odorless gas with a density of grams (the lightest gas) under standard conditions, and is poorly soluble in water. At -252, it becomes a colorless liquid, and at -259, it becomes a snowflake-like solid.

Physical Properties of Hydrogen:

1.Less dense than air (lighter than air) is the smallest of all gases.

Therefore, it is collected using the downward exhaust air method (bottle mouth).

It is used to fill and fill sounding balloons.

2.Insoluble in water.

Therefore, it does not react with water and can be collected by drainage.

3.Colorless, odorless, gaseous.

Chemical Properties:1Flammability.

Hydrogen gas is ignited to produce water.

Application: High energy fuel.

2.Reductiveness.

It can turn black copper oxide red and generate water at the same time.

Application: Smelting metals.