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

Academia - Collins - Pocket Scientific Dictionaries - Chemistry - English - French - Arabic Letter 4_ C


chalk
craie f

Chalk is a rock formed from the shells of marine animals, consisting mainly of calcium carbonate (CaCO3). These rocks are softer than... Limestone, which limits its uses.


charcoal
charbon m de bois

Charcoal . This charcoal is made by heating organic material, usually wood, in the absence of air. In this process, the volatile matter escapes and the remaining coal becomes composed mainly of carbon. Before coal was widely available, charcoal was used to make iron from iron ores. Some types of charcoal called “activated charcoal” can absorb small particles on its surface, so it is used in gas masks and in the sugar refining industry, and it has other uses where colored impurities must be removed from materials.


Charles' law
Loi f des gases favours

Charles' law. The volume of a given mass of gas depends on its temperature. If the temperature of the gas doubles (measured on the Kelvin scale), the volume of the gas doubles, provided that the gas pressure remains constant.


chemical change
Reaction of chemistry

Chemical change. A change that leads to the transformation of one or more chemicals into different substances. Such a change is usually accompanied by the release or taking of heat energy. See physical change.

chemical reaction
Reaction of chemistry

chemical reaction. See reaction.


chlorides
chlorides mpl

Chlorides. Compounds composed of chlorine and another element. Metal chlorides are usually ionic solids such as sodium chloride (NaCl) and barium chloride (BaCl).

Nonmetallic chlorides are covalent compounds, and are either low-boiling-point liquids such as quaternary chloromethane (CCl4) or gases such as hydrogen chloride (HCI).

Metal chlorides react with concentrated acids to produce hydrogen chloride gas.

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

Chlorides are tested by mixing a silver nitrate solution with the solution to be tested. If a white precipitate forms and then dissolves when the ammonia solution is added, the tested solution will be chloride.


chlorination
chloration f

Chlorination. Adding chlorine to drinking water and swimming pool water to kill dangerous germs. The term is also used to describe the reactions that take place between chlorine and hydrocarbons to produce chlorinated hydrocarbons.


chlorine (Cl2)
chlore m

Chlorine is a green gas at normal temperature. It is a highly reactive element from the group of halogen elements, Group VII. It has a suffocating effect and attacks lung and throat tissue if inhaled. It was used as a chemical weapon in World War II. Chlorine is found in nature in the form of chlorides, and sodium chloride is found abundantly in seawater. Chlorine is extracted by electrolysis of rock salt solutions, and is used in the manufacture of polymers (polyvinyl chloride (PVC), pesticides (DDT), disinfectants (TCP), and solvents (dry cleaning). The chlorine solution is used in Water is a bleaching agent.

Chlorine is an effective oxidizing agent that reacts immediately with most elements. It is made in the laboratory through the oxidation of concentrated hydrochloric acid, for example:

4HCl + MnO2 -> Cl2 + MnCl2 + 2H2O
(liquid) (aqueous) (gas) (solid) (aqueous)