أكاديميا - كولنز - معاجم الجيب العلمية - الكيمياء - انكليزي - فرنسي - عربي الحرف ٥_ e

Academia - Collins - Pocket Scientific Dictionaries - Chemistry - English - French - Arabic Letter 5_ E


ethers
ethers mpl

Etrate. Organic compounds have an oxygen atom bonded to two carbon atoms.
C4H10O

One of the most important ethers is diethyl ethane (ethoxyethane), which is usually known as just ethyl ether. This is ether, which was previously widely used as an anesthetic and is used today as a solvent for substances that do not dissolve in water. Highly flammable, air/ether mixtures constitute dangerous explosives. It is produced by the action of concentrated sulfuric acid in ethanol.


ethylene
ethylène m

Ethylene. See ethene.


ethyl ethanoate
ethyl ethanoate m

Ethyl ethanoate ester resulting from a reaction
Ethanol and ethanoic acid, used as a solvent for glues and paints.

ethyne (or acetylene)
acétylène m

ethene or acetylene). A gaseous alkyne
Flammable and forms explosive mixtures with air.

C2 H2
H--C = C--H

It can be produced by cracking petroleum products, although it is usually produced by the action of water on calcium carbide:

CaC2 + 2H2O → C2H2 + Ca(OH)2

(solid) (gas) (liquid) (solid)

This gas was previously widely used in lighting by burning it in lamps. These lamps were used in mines and for bicycles. Today, ethene is used to make chlorine and chloroethene, and then poly(chloroethene).

It is also used to produce very high temperatures by burning it in an oxy-acetylene torch for welding and cutting metals. Temperatures of up to 2700°C can be obtained.

evaporation
evaporation m

Evaporation. A change from a liquid state to a vapor state, which can occur at any temperature up to the boiling point. Evaporation occurs as a result of the escape of molecules from the liquid body into the atmosphere. Only a small percentage of molecules have enough escape energy at each moment, but all molecules escape with the passage of time. In general, the rate of evaporation is faster the lower the boiling point.

Some molecules have enough energy to escape.
Particles moving in a liquid at different speeds.

exothermic reaction
reaction m exothermique

An endothermic reaction In an endothermic reaction, thermal energy is released from the reactants to the surroundings. The bonds of the products have less energy than the bonds of the reactants. The products are more stable than the reactants. There are many common heat-producing reactions.
All combustion and neutralization reactions produce heat:
The Haber process

3H2(gas) + N2(gas) > 2NH2(gas)

And the contact process

2SO2(gas) + O2(gas) > 2CO3(gas)

Two endothermic reactions. The enthaly enthalpy changes are less than zero (negative).
See energy changes and endothermic reactions.


explosion
explosion f

Explosion. Rapid expansion of gas causes a shock wave.
Common explosives include gunpowder, nitroglycerin, and TNT. These materials react with oxygen if they are shocked and produce high temperatures. They also produce a lot of gas, and the gas molecules and the shock wave produced by the reaction from the explosion are transmitted to the outside with very great energy. This energy is what causes explosion damage.

In nuclear explosions, the huge amount of energy trapped within the nuclei of atoms is released.