أكاديميا - كولنز - معاجم الجيب العلمية - الكيمياء - انكليزي - فرنسي - عربي الحرف ٨_ c

Academia - Collins - Scientific Pocket Dictionaries - Chemistry - English - French - Arabic Letter 8_ C


corrosion
corrosion f

Eat . erosion. When a material corrodes, it means that it is chemically eaten away. A good example of this is the weathering of limestone in buildings due to rainwater that contains acids dissolved in it. As well as rusting steel. Corrosion begins on the surface, and the surface layer often protects the rest of the material, such as the oxide covering the aluminum surface.
This is not the case with rust, as the process of rusting steel infiltrates it until it completely corrodes. This makes rust very damaging and costly.


coulomb
coulomb m

Coulons Electrical charge is measured in coulons. It is the product of current (unit = ampere by unit time = second). If a current of 0.6 amperes flows for ten seconds, this means that colons of electricity pass through the circuit.


covalent bonds
liaisons fpl covalentes

Shared links. These bonds are formed by two atoms coming together and sharing their electrons, such as two hydrogen atoms each with one electron (e). The two atoms form a molecule of hydrogen (H2) by the two electrons forming a bond:
Thus, each shared pair of electrons produces one covalent bond.
Two hydrogen atoms (H)

Hydrogen molecule (H2)

Hydrogen chloride

Covalent bonds are usually found in compounds that contain only non-metallic elements, such as:

Carbon dioxide CO2
Hydrogen chloride HCI
Nitrogen dioxide NO2
Ammonia NH3
Phosphorous oxide (7) P2O5

It is also found in elements with an atomicity of two or more, such as:
Oxygen 02
Hydrogen H2
Bromine Br2
Nitrogen N2
Ozone O3
Chlorine Cl2
Sulfur S8
Phosphorous P4

Shared bonds that contain two electrons, i.e. a shared pair, are called single bonds. Many molecules contain double or triple bonds. Collaborative bonds are not as strong as ionic bonds.

covalent compounds
Composés multiple comparisons

Shared vehicles. Compounds that contain covalent bonds, are usually non-conductive, and have low melting and boiling points.

cracking
crackage m

Cracking is the process in which large hydrocarbon molecules are broken down into smaller hydrocarbon molecules, which is what happens in the petroleum refining industry. Small molecules are more valuable than large ones because they are the starting materials for producing materials such as polymers, such as polyethene and polypropene, and fuels, such as petrol.
And diesel fuel.

Many products are formed under different conditions:

Terms - - Products

high temperature

High temperature in the presence of steam

High temperature in the presence of a medium

High temperature and pressure in the presence of hydrogen

Process name

Thermal cracking
Steam cracking
Intermediate cracking
Hydrocracking

Products

Production of saturated and unsaturated molecules

The output is completely saturated


cryolite
cryolithe f

Cryolite. When extracting aluminum, bauxite (Al2O3) is dissolved in molten cryolite (NaAlF) at a temperature of 900 C, and then the mixture is electrolyzed. Aluminum is produced at the cathode.


crystal
crystal m

.Crystal. The atoms of solids (or their molecules or ions) are arranged in a specific three-dimensional geometric pattern. The shape of these atomic arrangements is determined by a crystal lattices. The shapes that the solid takes when it crystallizes.

Some examples of different crystal arrangements:

cube
Tetrahedral
Octahedral


crystallization
crystallization f

Crystallization The process by which crystals are formed. Crystals form in nature when molten rock cools and solidifies. Crystals are usually obtained in the laboratory from a solution. There are two main methods:

(1) The solution is left at a normal room temperature, and the solvent evaporates slowly, leaving crystals behind.
(2) A supersaturated solution is prepared at a temperature higher than that normal. When this solution cools, crystals form.


current
courant m

Electric current is the movement of electrons across a conductor, and is measured in units of amps. It is assumed that the current moves from the positive end to the negative end. However, electrons move from the negative end to the positive end. This difference results from the fact that electrons carry a negative electrical charge.


cyanide
cyanure m

Cyanide. Compounds containing a group of CN- atoms, the two most famous types are potassium cyanide (K+CN-) and hydrogen cyanide (H-C=N), both of which are highly toxic. Cyanides prevent the flow of energy into the body, making its effect very rapid.