أكاديميا - كولنز - معاجم الجيب العلمية - الكيمياء - انكليزي - فرنسي - عربي الحرف ٤_ h

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hydrogenation
hydrogenation f

Hydrogenation. The process of converting unsaturated compounds into saturated compounds by adding hydrogen to them. A catalyst such as nickel is used in this process, for example:
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Hydrogen carbonates (HCO3) carbonates of hydrogen

Hydrogen carbonate. Acid salts of carbonic acid, H2CO3. The most famous examples are:

Sodium hydrogen carbonate NaHCO: The commonly used household substance called bicarbonate of soda. It is found in self-rising flour and backing powder.

Calcium hydrogen carbonate (CalHCO3): Found in hard water because rainwater passes over carbonate rocks such as limestone:

CaCO3 + CO2 + H2O → CalHCO3) 2
(aqueous) (liquid) (aqueous) (solid)


hydrogen chloride (HCI)
acide m chlorhydrique

Hydrogen chloride. A colorless gas that is highly soluble in water, and its aqueous solution is called hydrochloric acid. The gas can be made by reacting the elements together or by treating sodium chloride with concentrated sulfuric acid:

H2 (gas) + CI2 (gas) → 2HCI (gas)

NaCl + H2SO4 → NaHSO4 + HCI
(gas) (solid) (liquid) (solid)

The gas reacts with ammonia to form dense white fumes of ammonium chloride:

(solid) NH4CI → (gas) HCI + (gas) NH3

The bonding in hydrogen chloride is covalent, but ions are formed when it is dissolved in a polar solvent such as water.


hydrogen halides
halides of hydrogen

Hydrogen halides. Gaseous compounds formed between hydrogen and halogens. They are covalent compounds that dissolve immediately in water to form an acidic solution containing halide ions, such as:

HBr + H2O → 2H2O + + Br-

(aqueous) (aqueous) (liquid) (gas)

Hydrogen fluoride HF
Hydrogen chloride HCI
Hydrogen bromide HBr
Hydrogen iodide HI


hydrogen ion
ion m d'hydrogen

Hydrogen ion. The positively charged hydrogen ion is a proton:
H → H + + e

It is a very interactive particle despite its very small size. In solution, this moiety combines with the molecules of the solvent. In water, it is represented by the oxonium ion:

Axonium ion H+ + H2O H3O +

The concentration of hydrogen ions in an aqueous solution is measured in pH units and gives a measure of the acidity of the solution (see hydroxide).


hydrogen peroxide (H₂O2)
water for oxygen

Hydrogen peroxide. This compound is usually used as an aqueous solution and immediately dissociates to give oxygen:
2H2O2 (aqueous) → 2H2O (gas) + O2 (liquid)

The manganese (IV) oxide intermediate accelerates the reaction. Hydrogen peroxide is used as a disinfectant and bleach in the home, and it is a strong oxidizing agent. The compound shortens hair color, making it blonde. It is used in industry to shorten paper pulp and natural fabrics. It is less damaging than the more powerful palace chlorine.